当前期刊: Colloid and Polymer Science Go to current issue    加入关注   
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Highly stretchable and thermally healable polyampholyte hydrogels via hydrophobic modification
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-25
    Gaukhar Toleutay, Esra Su, Sarkyt Kudaibergenov, Oguz Okay

    Abstract Aqueous solutions or gels of polyampholytes attract interest for more than half a century due to their several attractive properties. We present here thermally healable hydrophobically modified physical polyampholyte (PA) hydrogels based on oppositely charged 2-acrylamido-2-methylpropane-1-sulfonic acid sodium salt (AMPS) and (3-acrylamidopropyl) trimethylammonium chloride (APTAC) monomers. PA hydrogels were prepared via micellar polymerization technique in the presence of the hydrophobic monomer n-octadecyl acrylate (C18A) in aqueous sodium dodecyl sulfate (SDS) solutions. Charge-balanced PA hydrogels containing 60–90% water exhibit a high tensile strength and stretchability of up to 202 kPa and 1239%, respectively. Above 7 mol% C18A, swollen hydrogels containing around 90% water exhibit much better mechanical properties as compared with the corresponding as-prepared ones because of the stronger hydrophobic interactions in the absence of SDS micelles. Cut-and-heal tests conducted at 50 °C reveal a complete healing efficiency with respect to Young’s modulus for all as-prepared PA hydrogels within 1–4 h. Graphical abstract .

    更新日期:2020-01-26
  • Fabrication of inverse core–shell and Janus-structured microspheres of blends of poly(4-butyltriphenylamine) and poly(methyl methacrylate)
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-24
    Shu Kikuchi, Ryoka Shoji, Saki Yoshida, Shinji Kanehashi, Guang-Hui Ma, Kenji Ogino

    Abstract We here report the facile fabrication of inverse core–shell and Janus structured particles consisting of poly(4-butyltriphenylamine) (PBTPA) and poly(methyl methacrylate) (PMMA) via a solvent evaporation from solution droplets of a polymer blend dispersed in an aqueous phase. Janus structured composite particles in which the PBTPA domain was partially coated by the PMMA domain were obtained using poly(vinyl alcohol) (PVA) as a suspension stabilizer. On the other hand, when sodium dodecyl sulfate (SDS) was added as a surfactant together with PVA, “inverse core–shell” particles in which the PMMA core was covered by the PBTPA shell were formed as well as Janus particles. TEM observation showed that the PMMA core was located at the center of the sphere and PBTPA layer has uniform thickness in inverse core–shell particles. The increase of the composition of PBTPA or the concentration of SDS increased the ratio of the inverse core–shell particles to the Janus ones. Graphical abstract

    更新日期:2020-01-26
  • Structural dynamics of tween-based microemulsions for antimuscarinic drug mirabegron
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-24
    Muhammad Faizan Nazar, Ayesha Mujeed, Muhammad Yasir Siddique, Muddassar Zafar, Muhammad Atif Saleem, Asad Muhammad Khan, Muhammad Ashfaq, Sajjad Hussain Sumrra, Muhammad Zubair, Muhammad Nadeem Zafar

    Abstract Microemulsions (μEs)-based drug delivery is known to be superior as well as effective due to customizable and easy management, efficiency and capability, and quick drug absorption over a wide range of targets. Herein, two μE formulations were established comprising of clove oil (as oil phase), water (as aqueous phase), Tween-80 (as surfactant), isopropanol, and methanol (as cosurfactant) for formulation A (μE-A) and formulation B (μE-B), respectively, and further used for the encapsulation of an antimuscarinic drug, mirabegron (MBG). Multiple complementary measurements, namely, electrical conductivity (σ), viscosity (η), and optical microscopy, show the existence of phase transition from W/O to O/W μE via intermediate bicontinuous channels. MBG showed long storage stability as well as good solubility i.e. 3.0 and 2.5 wt% at pH 6.4 in optimum μE-A and μE-B, respectively. Furthermore, no apparent aggregation of MBG was observed, as revealed by scanning transmission electron microscopy and peak correlations of IR analysis, suggesting the stability of MBG inside the formulations. Likewise, fluorescence detection senses the interfacial environment of MBG molecules in the examined formulations that could be vital for understanding the mechanism of controlled drug release. Graphical abstract Structural Dynamics of Tween-Based Microemulsions for Antimuscarinic Drug Mirabegron

    更新日期:2020-01-24
  • Is it feasible to perform an emulsion polymerization using a deep eutectic solvent as continuous phase?
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-22
    Itzel Quintanar, Jorge Herrera-Ordonez, María G. Pérez-García, Enrique Jimenez-Regalado, Josué D. Mota-Morales

    Abstract Emulsion polymerization using a deep eutectic solvent (DES) as continuous phase was performed for the first time. Considering that the electrolytes concentration in a DES is much higher than the one required to cause catastrophic coagulation in the analogous aqueous colloidal system, this result is notable and interesting. Hypothesis and questions that can guide future research on this regard are drawn. Graphical abstract

    更新日期:2020-01-22
  • Tuning the pore architectures of hierarchically porous carbons from high internal phase emulsion template by polyaniline-coated CNTs
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-16
    Yulai Zhao, Jing Zhang, Mengzhi Wei, Longqiang Xiao, Bin Huang, Linxi Hou

    Abstract The work reported the preparation of hierarchically porous carbons (HPCs) with adjustable pore architectures using high internal phase emulsion (HIPE) template with the presence of polyaniline-coated carbon nanotubes (PANI-CNTs). PANI-CNTs were obtained via in situ polymerization of aniline in CNT suspension as confirmed by scanning electron microscope (SEM) and thermogravimetric analysis (TGA). Porous polydivinylbenzene (PDVB) monoliths were prepared by polymerizing the continuous phase of HIPE with PANI-CNTs dispersed in the internal phase. After carbonization and activation, HPCs with variable pore architectures were obtained. As observed by SEM, the PANI-CNTs showed notable influence on the pore architectures of PDVBs and HPCs. The void size of PDVB precursor reduced with the increase of the mass ratio of PANI to CNT, as well as the content of PANI-CNTs. Nitrogen adsorption/desorption measurements indicated the coexistence of mesopores and micropores, namely, hierarchical pores. The specific surface area (SSA) of HPC increased along with the content of PANI-CNTs from 1893 to 2392 m2/g. The capability of HPCs as the electrode material of supercapacitor was evaluated via electrochemical tests. The results indicated that the HPC with optimized pore architecture showed a higher specific capacitance (168.6 F/g) than the contrast sample (130.9 F/g) at 1 A/g. The better capacitance performance of HPC obtained with the presence of PANI-CNTs could be attributed to the reasonable hierarchical pores, higher SSA, and higher graphitization degree.

    更新日期:2020-01-17
  • Molecular interactions between Pluronic F127 and saponin in aqueous solution
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-16
    Rosemaire S. S. de Oliveira, Nélida S. Marín Huachaca, Monique Lemos, Natália F. Santos, Eloi Feitosa, Luiz C. Salay

    Nanotechnology is important for the development of new materials capable to improve the development of novel drug delivery systems. Such systems may result in more efficient therapeutic effects with reduced toxicity and extended time in the organism and increase in bioavailability, biocompatibility, and solubility of drugs. Here it was investigated the interaction between the triblock copolymer Pluronic F127 (F127) and a natural bioactive amphiphilic saponin (SAP), extracted from Glycyrrhiza glabra roots, aiming to form micelle-like F127-SAP complexes in a pH 7.4 HEPES buffered aqueous solution, with potential nanobiotechnological applications. Differential scanning calorimetry (DSC), dynamic light scattering (DLS), and dynamic electrophoretic light scattering (DESL) were the techniques used in this investigation, at varied SAP concentrations below and above CMC at fixed 500 μM F127. The SAP-F127 molecular interactions were verified by changes in the critical micellar temperature (CMT) of F127 obtained from the DSC thermograms, while DLS and DELS data showed, respectively, the formation larger structures of the complexes relative to the single Pluronic micelles and zeta potential (ζ) values ranging from ca − 6.5 to − 9 mV, on varying the SAP concentration. Combined, these results indicate the formation of micelle-like complexes, with structure dependent on the SAP concentration, as highly promising agents in nanobiotechnology applications.

    更新日期:2020-01-16
  • Rheological properties of multi-walled carbon nanotubes/silica shear thickening fluid suspensions
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-14
    Minghai Wei, Yinru Lv, Li Sun, Hong Sun

    Abstract In this study, the rheological properties of multi-walled carbon nanotubes/silica shear thickening fluid suspensions (MWCNT/SiO2-STFs) with different concentrations were investigated. Through scanning electron microscopy, it was found that the MWCNTs had a strong adsorption on silica nanoparticles, and a “new particle group” containing MWCNTs was formed in the samples. The rheological results demonstrate that MWCNT/SiO2-STFs have significant shear thinning and shear thickening phenomena, and when the mass fraction of MWCNTs is 0.8%, the STFs have the best shear thickening performance; the viscosity increases by 191% while the critical shear rate decreases by 60.19%. The results also reveal that the rheological property of MWCNT/SiO2-STFs is effectively improved by increasing the plate spacing, particularly when their mass fraction is low. Moreover, the temperature sensitivity of MWCNT/SiO2-STFs is still dominated by the silica nanoparticles. Without affecting their temperature sensitivity, the MWCNTs can significantly enhance the shear thickening performance of silica-based STFs.

    更新日期:2020-01-15
  • Luminescent lanthanide metallogels: situ fabrication, self-healing and rheological properties
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-13
    Min Xue, Ming Chen, Wenhao Chang, Ruiyang Chen, Pengna Li

    We have presented a simple method for situ fabrication of photoluminescent lanthanide metallogels. A series of lanthanide metallogels could be rapidly formed through mixing the aqueous solution of Tb3+ or Eu3+ and organic solution of synthesized aromatic carboxylic ligands (DCn, n = 14, 16,18) at room temperature. The gelation tests revealed that the ligand with longer alkyl chain (DC18) showed stronger gelling abilities, indicating that the structure of non-coordinated groups in ligand molecules could affect self-assembly processes and, hence, the microstructures and properties of lanthanide metallogels. FT-IR measurements demonstrated that the driving force of formation of the metallogels was the coordination interaction between DCn and Tb3+ or Eu3+. XRD analysis revealed that DC14 metallogels took a mixture of hexagonal and tetragonal packing modes. All obtained metallogels have shown typical luminescent emissions of the lanthanide complex. In particular, DC18/Tb(NO3)3 metallogel in DMF/H2O (v:v = 1:1) has shown excellent self-supporting, self-healing, film-forming, and rheological properties.

    更新日期:2020-01-14
  • Synthesis and characterization of TiO 2 /acrylic acid-co-2-acrylamido-2-methyl propane sulfonic acid nanogel composite and investigation its self-healing performance in the epoxy coatings
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-10
    Erfan Rezvani Ghomi, Saied Nouri Khorasani, Mohsen Karimi Kichi, Mohammad Dinari, Shahla Ataei, Mohammad Hossein Enayati, Mohammad Sadegh Koochaki, Rasoul Esmaeely Neisiany

    Abstract In the present study, the surface of titanium dioxide (TiO2) nanoparticles was modified with superabsorbent gel based on acrylic acid (AA) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) via in-situ polymerization using 3-(triethoxysilyl) propyl methacrylate (MPS) as a silane coupling agent. The synthesized TiO2 nanogel composite was then incorporated into a commercial epoxy resin in different weight percent (1, 2, and 4) to prepare an effective self-healing epoxy coating. The chemical structure and surface morphology of the prepared nanogel composite were evaluated by Fourier transform infrared (FTIR), X-ray diffraction (XRD), and Field Emission Scanning Electron Microscopy (FESEM). Furthermore, to calculate the weight ratio of the inorganic to organic materials, the ash content test was employed. The effectiveness of the TiO2 nanogel composite as the self-healing material in the epoxy resin was assessed in 3.5 wt.% NaCl solution by potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS).

    更新日期:2020-01-11
  • Synthesis of sub-100 nm PMMA nanoparticles initiated by ammonium persulfate/ascorbic acid in acetone-water mixture
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-10
    Xia Li, Yun Huang, Yi Dan

    Abstract The polymer nanoparticles with size less than 100 nm can be prepared by surfactant-free emulsion polymerization (SFEP) with co-solvent, but it needs to be conducted in high temperature at over the azeotropic point of the solution. In the present study, the redox initiator of ammonium persulfate/ascorbic acid (APS/ASA) was applied to reduce the reaction temperature of SFEP with acetone as co-solvent. The effects of temperature, acetone content, monomer concentration, and initiator on the particle size of poly(methyl methacrylate) (PMMA) were investigated to control average diameter of PMMA nanoparticles (PNs) efficiently. The results showed that the PMMA nanoparticles with 45 nm in diameter and uniform size (PDI < 0.05) can be synthesized conveniently through controlling the ratio of APS/ASA.

    更新日期:2020-01-11
  • Generation of spatially ordered metal–polymer nanostructures in the irradiated dispersions of poly(acrylic acid)–poly(vinylimidazole)–Cu 2+ complexes
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-02
    Deniz E. Dağaş, Gurgen V. Danelyan, Mohammadreza Ghaffarlou, Elena A. Zezina, Sergei S. Abramchuk, Vladimir I. Feldman, Olgun Güven, Alexey A. Zezin

    The generation of metal nanostructures by radiation-induced reduction of copper ions in aqueous dispersions of macromolecular complexes of poly(acrylic acid) and polyvinylimidazolе has been studied in the pH range of 2.3–4.3. It was shown that an effective coordination number of Cu2+ in the complex with polymer units decreased at lower pH, which resulted in dramatic increase of the nanoparticle formation rate. As demonstrated by transmission electron microscopy, using the poly(acrylic acid)–polyvinylimidazolе–Cu2+ complexes as precursors allows one to control the nanoparticle size and promotes assembling of spatially ordered supramolecular structures. As revealed by dynamic light scattering, decreasing the medium pH leads to ripening of the poly(acrylic acid)–polyvinylimidazolе–Cu2+ particles. The obtained results provide an evidence for strong effect of the pH value on the spatial organization of nanoparticles in irradiated suspensions. In the case of less acidic medium (at pH 3), assembling of nanoparticles occurs in flabby interpolymer particles, whereas at lower pH the metal nanoparticles are produced in the templates of the perfect macromolecular nanostructures.

    更新日期:2020-01-04
  • Spray-dried microparticles composed of carboxylated cellulose nanofiber and cysteamine and their oxidation-responsive release property
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-02
    Tae Hoon Kim, Seung-Hwan Lee, Jin-Chul Kim

    TEMPO-modified cellulose nanofiber (TM CNF) microparticles (MPs) incorporating cysteamine (CA) were prepared by a spray-drying method. MPs on SEM micrographs were flat wrinkled balls-like and less than 10 μm in diameter. The energy-dispersive X-ray spectroscopy, the elemental mapping, and the X-ray photon spectroscopy were performed to understand the content and the distribution of CA in the TM CNF MPs. FT-IR spectroscopy showed that the thiol groups of CA molecules contained in MPs were oxidized by the treatment of H2O2. According to DSC analysis, CA contained in the MPs exhibited the melting point at a lower temperature (ca. 50–53 °C) than free CA (ca. 69 °C). The volume mean diameter of the MPs was 12.1 to 13.8 μm. The release of FITC-dextran loaded in MPs was promoted when H2O2 solution was used as a release medium. The promoted release could be ascribed to the oxidization-induced reorientation of CA molecules and the subsequently occurring dislocation of TM CNF.

    更新日期:2020-01-04
  • Investigations on the compatibilization between poly(lactic-co-glycolic acid)/poly(trimethylene carbonate) blends and poly(lactide-co-trimethylene carbonate)
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-02
    Jin Qi, Shaomin Feng, Yu Zhang, Hechun Chen, Chengdong Xiong

    Abstract In this study, the effect of different contents of poly(lactide-co-trimethylene carbonate) (PLT) as a compatibilizer on the blends of PLGA and PTMC has been investigated. The PLGA/PTMC/PLT ternary composites were prepared by using the solution co-precipitation method. The PLT component played a very important role in determining internal structure, and thermal, mechanical, and hydrophilic properties of whole composites. Our results showed that the PLT addition made the glass transition temperature of PLGA and PTMC close to that of each other and improved their compatibility. When the amount of PLT addition was 3 wt%, the two-phase interface of the composite fracture surface almost disappeared, which further demonstrated that PLT could improve the interfacial compatibility of PLGA and PTMC. The tensile strength and tensile modulus and the elongation of the PLGA/PTMC/PLT composites were 54.01 ± 2.1 MPa, 1.11 ± 0.05 GPa, 49.29 ± 3.6% respectively after the 3 wt% random copolymers was added. The results of XRD and POM showed that the crystalline morphology of the composites was spherocrystal, where the second crystalline phase was not found. Interestingly, PLT reduced the hydrophilicity of PLGA/PTMC/PLT composites. In conclusion, PLGA/PTMC/PLT composites are expected to have a fascinating role in the field of bone defect repair. Graphical abstract

    更新日期:2020-01-02
  • Identification of aqueous reservoirs in poly(alkylcyanoacrylate) nanoparticles
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2020-01-02
    O. Thomas, L. Lemaire, J. P. Benoit, P. Saulnier

    Abstract Poly (n-butylcyanocrylate) nanocapsules were obtained by interfacial polymerization from a water-in-oil microemulsion. The latter was composed of pharmaceutically acceptable excipients such as Labrafac lipophile WL 1349 (oil), Plurol oleique CC497 (surfactant), and Labrasol (co-surfactant) and was able to incorporate 20% aqueous phase. Pure n-butylcyanoacrylate monomer (without any dilution in a halogenated solvent) was added to the microemulsion in order to obtain an oily suspension of biocompatible and biodegradable aqueous core nanocapsules. Finally, in order to provide a direct evidence of the presence of water within the nanocapsules, a mass balance and nuclear magnetic resonance analysis were performed. The results showed that the presence of water and transmission electronic microscopy confirmed a hybrid structure of the final nanosystem, between a genuine nanocapsule and a matrix system: a nanosystem with multicavities filled with water. Graphical abstract

    更新日期:2020-01-02
  • Electrophoresis of pH-regulated zwitterionic soft particle: a semi-analytical study
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-12-11
    Bharti, Partha P. Gopmandal, R. K. Sinha, H. Ohshima

    In this article, we made a parametric study on the electrophoresis of charge-regulated soft particle. We consider a typical situation where the outer polyelectrolyte layer (PEL) carries zwitterionic functional group (e.g., succinoglycan). In addition, the inner rigid core is considered to be made of either silicon dioxide (SiO2) or titanium dioxide (TiO2), which produces zwitterionic surface charge. The mathematical model adopted here is based on the Poisson-Boltzmann equation for electric potential and Darcy-Brinkman and Stokes equation for the fluid flow across the surface PEL and electrolyte medium, respectively. In our current study, we have restricted ourselves with the low charge and weak electric field assumption. Using semi-analytical method, we solve the governing equations and electrophoretic mobility of core-shell particle is obtained. We have studied extensively the effects of the pH and concentration of bulk electrolyte, charge properties of the inner core surface and outer PEL, radius of the inner core, and thickness of outer PEL, on the overall electrophoretic behavior of the undertaken particle. We have also highlighted the change in sign in electrophoretic mobility by regulating the pertinent parameters governing the problem.

    更新日期:2019-12-11
  • Electrophoretic mobility of a cylindrical colloidal particle with a slip surface
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-12-07
    Hiroyuki Ohshima

    General expressions of the electrophoretic mobility-zeta potential relationship for a cylindrical colloidal particle with a hydrodynamically slipping surface in an aqueous electrolyte solution under a transverse or tangential electric field are obtained on the basis of the Navier boundary condition. Approximate expressions for the electrophoretic mobility of cylindrical particles carrying a low zeta potential are derived. As in the case of a sphere, the electrophoretic mobility of a cylinder increases with increasing slip length, which characterizes the hydrophobicity of the particle surface.

    更新日期:2019-12-07
  • Improved self-healing properties and crack growth resistance of polydimethylsiloxane elastomers with dual-capsule room-temperature healing systems
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-12-07
    Zhenhang Yin, Jianhua Guo, Junxia Qiao, Xuming Chen

    Two types of microcapsules were prepared by in situ polymerization with poly(urea-formaldehyde) (PUF) as the shell material. The core materials of the microcapsules contained Sylgard 184A gum (labeled as capsule I) and hydrogen silicone oil (labeled as capsule II). Capsule types I and II were characterized by optical microscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Capsule types I and II were incorporated into silicone rubber polydimethylsiloxane (PDMS) at an appropriate proportion to construct a self-healing system. The healing efficiency initially increases and then decreases with the increased proportion and addition of the two capsules. The maximum self-healing efficiency is obtained with a value of 70.5% by the incorporation of 10 wt% miscellaneous microcapsules when the weight proportion of capsule types II and I is 0.6. Cracks in the PDMS/capsule composites almost disappear with an increased healing time of up to 24 h at room temperature, indicating improved healing properties with a prolonged healing time.

    更新日期:2019-12-07
  • A unified analysis of the coagulation behaviour of silica hydrosols—when the colloid and polymer science meet
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-12-06
    Jiří Škvarla, Juraj Škvarla

    An allegedly anomalous behaviour of aqueous dispersions of silica has attracted continually a great attention from Thomas Graham’s time. However, even recent coagulation experiments with apparently well-defined colloidal silica spheres are not interpretable when their surface is assumed intact in contact with water. In fact, various explanations such as a hairy layer of polysilicic acid and the hydration layer on the silica surface are well-known but not proven accompaniments of the hydration process. It has been previously suggested (Skvarla, J., Langmuir, 29:8809–8824, 2013) basing on a combination of the soft-sphere model of colloids, surface charge data, and the Flory-Donnan theory that a swellable polyelectrolyte gel-like layer develops inherently on the surface of highly charged silica in aquoeus KCl solutions. Here, we support this rationalization by extending the coagulation analysis. Results are also discussed from the standpoint of approaches associated with the traditional and extended DLVO theories.

    更新日期:2019-12-06
  • Structure and performance of waterborne polyurethane-acrylate composite emulsions for industrial coatings: effect of preparation methods
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-12-05
    Yunjiao Deng, Chao Zhou, Qiuxue Zhang, Mingyao Zhang, Huixuan Zhang

    Waterborne polyurethane-acrylate (WPUA) composite emulsions were prepared by the physical blending method, graft emulsion polymerization method, and interpenetrating network (IPN)-based method using polytetramethylene glycol (PTMG), isophoronediisocyanate (IPDI), and acrylic monomers (methyl methacrylate (MMA) and butylacrylate (BA)) as the main raw materials. The WPUA polymers were characterized based on their water resistance, morphologies, thermal, spectroscopic and mechanical properties. Graft WPUA film had the highest tensile strength and the best thermal stability, indicating that the strength of the chemical bond between PU and PA plays an important role in modulating the performances of the WPUA films. The results showed that the graft WPUA has excellent integrated properties and thus a potential application in the coating industry.

    更新日期:2019-12-06
  • Swelling of multi-responsive spherical polyelectrolyte brushes across a wide range of grafting densities
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-12-05
    Danish Iqbal, Jiajun Yan, Krzysztof Matyjaszewski, Robert D. Tilton

    Multi-stimulus responsive weak polyelectrolyte brushes were grafted by surface-initiated atom transfer radical polymerization from spherical silica nanoparticles across a wide range of grafting densities approaching the limit of close packing of grafting sites: a regime not previously explored in the brush swelling literature. Brushes consisted of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) homopolymers or poly(2-(dimethylamino)ethyl methacrylate)-r-poly(4-metharyloyloxyazobenzene) random copolymers P (DMAEMA-r-MOAB) and were subjected to pH-, temperature-, and photoisomerization-induced swelling and deswelling. Homopolymer brushes were prepared at grafting densities ranging from 0.12 to 1.4 nm−2 and number average degrees of polymerization ranging from 300 to 1200. Two copolymer brushes with 8 mol% and 13 mol% of the nonionizable, photoresponsive MOAB units were compared with homopolymer brushes prepared at similar grafting densities and degrees of polymerization. Dynamic light scattering was used to measure the hydrodynamic radius of grafted nanoparticles, and thus brush thickness, in water. Brush swelling in response to increased DMAEMA protonation followed a single scaling behavior across the full range of degrees of polymerization and grafting densities. Incorporating azobenzene-containing MOAB comonomers introduced a modest photoresponsive control of brush swelling and decreased the brush thickness relative to the comparable PDMAEMA homopolymer brush, without affecting the scaling with respect to protonation. PDMAEMA brushes exhibited a pH-dependent lower critical solution temperature behavior, resulting in a thermal collapse of up to 50% upon heating. This work demonstrates that scaling behaviors previously tested at low grafting densities hold for extremely high grafting densities and that they are unaffected by moderate nonionizable comonomer content.

    更新日期:2019-12-05
  • The immobilization of lanthanide (III) cations on a polymer containing quaternary ammonium nitrogen: influence of the temperature and pH, process kinetics
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-12-05
    Vasile Gutsanu, Cristina Grecu

    The immobilization of lanthanide (III) cations on the Purolite A-400, a cross-linked polymer containing –R4N+ groups, was investigated. This type of polymers theoretically cannot retain metal cations from solutions. We assume that cations sorption on this polymer takes place due to the formation of jarosite mineral–type compounds. By increasing the temperature in the range of 0–60 °C, the cations sorption increases slightly but in the pH range of 2–6, it increases more considerable in the following order: La3+˂ Nd3+ ˂ Eu3+ ≈ Er3+. The sorption at 21 and 50 °C is adequately described by the pseudo-first-order (PFO) kinetic model, and the limiting step of the rate which decreases in order Er3+ ˃ Eu3+ ˃ Nd3+ ˃ La3+ is internal diffusion.

    更新日期:2019-12-05
  • Electrospun PCL-based polyurethane/HA microfibers as drug carrier of dexamethasone with enhanced biodegradability and shape memory performances
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-12-04
    Haitao Lv, Dongyan Tang, Zhaojie Sun, Jingru Gao, Xu Yang, Shuyue Jia, Jing Peng

    Shape memory polymers (SMP) with better biodegradability and better stability have great potential applications in biomedical fields, such as the drug carriers or the tissue engineering scaffolds. In this study, poly(ε-caprolactone)(PCL)-based polyurethane(PU) microfibers were fabricated with the containing of hydroxyapatite(HA) to enhance the biodegradability and to exhibit excellent shape memory performance. The composition, the morphology, the thermal stability, and the mechanical properties of the microfibers were characterized and detected using Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1HNMR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC). and dynamic mechanical analysis (DMA), etc. And dexamethasone was selected as drug model to investigate the delivery and release behaviors of the carrier of the microfibers. It was revealed that HA enhanced the degradation rate of the shape memory polyurethane (SMPU) fibers, and the fibers could guarantee a sustained long time drug release. The detection on the shape memory performance found that, with the different addition amounts of HA, the composite microfibers of (SMPU) and HA exhibited the different shape memory transition temperature (Ttrans) values. And with the addition of 3 wt% of HA, the excellent shape recovery ratios of Rr (> 97%) and the shortest recovery time of ~ 6 s could be obtained. With further increase of the amounts of HA, the recovery force and the recovery time were reduced and prolonged, respectively. The obtained results proved that the biodegradable SMPU/HA composite microfibers have more valuable application prospects in biomedical fields.

    更新日期:2019-12-04
  • Physical principles of the formation of a nanoparticle electric double layer in metal hydrosols
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-11-23
    A. P. Gavrilyuk, I. L. Isaev, V. S. Gerasimov, S. V. Karpov

    The Brownian dynamics method is employed to study the formation of an electrical double layer (EDL) on the metal nanoparticle (NP) surface in hydrosols during adsorption of electrolyte ions from the interparticle medium. Also studied is the charge accumulation by NPs in the Stern layer. To simulate the process of the formation of EDL, we took into account the effect of image forces and specific adsorption, dissipative and random forces, and the degree of hydration of adsorbed ions on the EDL structure. The employed model makes it possible to determine the charge of NPs and the structure of EDL. For the first time, the charge of both the diffuse part of EDL and the dense Stern layer has been determined. A decrease in the electrolyte concentration (below c < 0.1 mol/l) has been found to result in dramatic changes in the formation of the Stern layer.

    更新日期:2019-11-26
  • Association behavior and fluorescence quenching between cationic zinc porphyrin pendant groups on water-soluble polymers and anionic iron porphyrin guests
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-11-16
    Kewei Ding, Hongli Liu, Min Zhang, Chenxi Qu, Zhongxue Ge, Taoqi Li

    An amphiphilic cationic tripyridiniumylporphyrin monomer, i.e., ZnTrMPyP, was synthesized and copolymerized with acrylamide in water and dimethyl sulfoxide, respectively, to prepare the water-soluble random copolymer P-D and microblock copolymer P-W. The association behavior and fluorescence quenching between the copolymers and tetra(p-sulfonato phenyl)porphyrin (Fe(III)TSPP(Cl)) were studied via absorption and emission spectra. The results showed that relatively discrete pendant groups of ZnTrMPyP within P-D could form a ground state complex with FeTSPP by electrostatic interactions, and both static and dynamic mechanisms were active in this quenching process. In contrast, the microblock porphyrin pendant groups within P-W interacted with FeTSPP as an entity, and static quenching was dominant in this process. Salt effects on the formation of the copolymers and FeTSPP complex were also investigated through the addition of KNO3, and the results showed that this association can be weakened by the electrostatic shielding effect, and the fluorescence quenching constant could be reduced.

    更新日期:2019-11-17
  • Dimeric camptothecin-loaded mPEG-PCL nanoparticles with high drug loading and reduction-responsive drug release
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-11-14
    Yanwei Chi, Zhiying Wang, Jie Wang, Wenpei Dong, Pengyang Xin, Jingjing Bi, Tao Jiang, Chang-Po Chen

    Camptothecin (CPT) is a potent and broad-spectrum anti-tumor drug, but its clinical application is limited due to its poor water solubility, toxicity, and low drug-loading potential. Different delivery protocols have been developed to optimize the therapeutic effects of CPT. In this study, CPT was modified into a dimer (CPT-Mal-CPT), in which two CPT molecules are connected by a reduction-responsive maleimide thioether bond. Moreover, biocompatible methoxy poly(ethylene glycol)-b-poly(ε-caprolactone) (mPEG–PCL)-loaded CPT-Mal-CPT nanoparticles were prepared to overcome the limits of CPT application. The power X-ray diffractometer (PXRD) results indicate low crystallinity and amorphous nature of CPT-Mal-CPT. The CPT-Mal-CPT-loaded micelles showed a drug-loading content of 9.6% and a drug-loading efficiency of 56%. In addition, dimeric CPT micelles showed reduction-responsive release under 10-mM dithiothreitol (DTT), while negligible CPT release was detected in the absence of DTT. MTT assay indicated that cytotoxicity of dimeric CPT micelle was similar to free CPT.

    更新日期:2019-11-14
  • Controlled gel research: the effect of ethanol for delaying the polycondensation of tetraethyl orthosilicate-dimethyldiethoxysilane
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-11-09
    Xianni Song, Junhua Zhang

    In this study, the effect of ethanol for delaying the polycondensation of silanol in the co-hydrolysis-condensation of tetraethyl orthosilicate-dimethyldiethoxysilane was first explored and demonstrated by varying the amount of ethanol under low-water content and acid-catalyzed. On the basis of this, the controllability of the sol-gel process is realized, and the calculation formula of the gel formation time is provided. The experiment shows that the storage gel time and the reaction gel time are extended from 75 h to at least 4584 h, or from 20 to 65 h with the increase of ethanol concentration, respectively. And we observed the microscopic process of solution-sol-gel transition by light transmission microscope. The sol-gel process established in this experiment gives a mechanism reference for future research.

    更新日期:2019-11-11
  • The effects of grafting density and charge fraction on the properties of ring polyelectrolyte brushes: a molecular dynamics simulation study
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-11-09
    Qing-Hai Hao, Li-Xiang Liu, Gang Xia, Li-Yan Liu, Bing Miao

    Using molecular dynamics simulations, the flexible ring polyelectrolyte chains tethered to a planar substrate and immersed in good solvents are investigated systematically. Two sets of simulations are performed to explore the effects of grafting density and charge fraction, respectively. Both the monovalent and trivalent counterions are considered. The height of the brush H follows a scaling relation with grafting density (~σgν) and charge fraction (~fν). The values of the exponents are different from those of the linear counterparts. Through a careful analysis on the distributions of monomers and counterions, pair correlation functions of monomer-monomer and monomer-counterion, as well as the fractions of trivalent counterions in four states, the equilibrium structures of the ring PE brushes are examined in detail. Furthermore, a brief comparison with the ‘equivalent’ linear brush is carried out. Also, our results can serve as a guide for improving the performance of ring polyelectrolyte brushes as unique surface modifiers.

    更新日期:2019-11-11
  • Bio-based castor oil organogels and investigations on their anion-tuning properties
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-11-07
    Hima Bindu, Aruna Palanisamy

    We report here bio-based N-(2-hydroxyethyl) ricinoleic amide (NHRA) a derivative of castor oil, as a low molecular weight gelator showing good gelation in organic solvents. NHRA gelator molecules exhibited thermoreversible gelation in specific tested organic solvents such as aniline and 1,4 dioxane. The gelator molecules are self-assembled through intermolecular hydrogen bonding and van der Waals interactions which are the determining factors for the organogel formation as confirmed by FT-IR spectroscopy. Differential scanning calorimetry (DSC) measurements show the phase transition of gels from gel to solution state and strongly depend by varying the concentration of the gelator. The supramolecular aggregation of gelators in the gel state led to viscoelastic nature of the organogels and was studied by rheology. Morphological studies reveal the presence of lamellar fibrous-like structures, which are responsible for the molecules to aggregate into 3D network. The synthesized organogel acts as a host for anions that change the physical state from gel to sol by disruption of intermolecular hydrogen-bonding interactions. The propensity of the material to exhibit anion-responsive behavior is attributed to the presence of amide linkages, under which deprotonation of N–H fragments occur upon the addition of anions, as confirmed by 19F NMR and FT-IR spectroscopy. These results indicate that NHRA gelator can be prospective candidate for sensing applications

    更新日期:2019-11-11
  • Effect of hydrodynamic size on colloidal stability and lifetime of Mn-Zn magnetic fluids
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-11-05
    Navjot Kaur, Bhupendra Chudasama

    For transformer cooling applications, magnetic particles need to be dispersed in carrier fluids with high colloidal stability for a long period without significant degradation. However, stability of the suspension, especially the long term colloidal stability is a crucial factor for the applications in power transformers because aggregation of particles could cause clogging of micro-channels in transformers. In this article, we have reported effect of hydrodynamic size on the colloidal stability of Mn1-xZnxFe2O4 (MZ) nanoparticles (NPs)–based magnetic fluids. Lifetime of fluids has been determined from the increase in hydrodynamic size of magnetic NPs due to aggregation. Colloidal stability of fluids decreases with increase in the polydispersity of fluids caused by the enhanced dipole interactions between NPs resulting in the aggregation of NPs in chain-like structures.

    更新日期:2019-11-06
  • Crosstalk between responsivities to various stimuli in multiresponsive polymers: change in polymer chain and external environment polarity as the key factor
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-10-31
    Martin Hruby, Petr Štěpánek, Jiří Pánek, Christine M. Papadakis

    Multiresponsive polymers offer a wealth of possibilities to design switchable materials which respond to more than one stimulus. We describe first the response of polymers to a single external stimulus, namely to temperature, light, pH value, redox changes, and low molecular weight species, and discuss the influence of these stimuli on the polymer chain polarity. Then, we review multiresponsive homopolymers and statistical and block co-polymers. Finally, we discuss the similarity of multiresponsive synthetic polymers to biopolymers. As a conclusion, multiresponsiveness opens up a broad area for combining different properties in one system, enabling numerous possible applications.

    更新日期:2019-11-01
  • Preparation and characterization of dithiocarbazate Schiff base–loaded poly(lactic acid) nanoparticles and analytical validation for drug quantification
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-10-31
    Thacilla Ingrid de Menezes, Rebeca de Oliveira Costa, Rute Nazaré Fernandes Sanches, Denise de Oliveira Silva, Rodrigo Luis Silva Ribeiro Santos

    Dithiocarbazate Schiff bases have been reported as a class of compounds that exhibit a wide range of pharmacological activities against neglected diseases such as malaria, trypanosomiasis, and tuberculosis. This work reports the encapsulation of the 1-(S-benzyldithiocarbazate)-3-methyl-5-phenyl-pyrazole (DTC) into biodegradable polymeric nanoparticles (NPs) of poly(lactic acid) (PLA) aiming potential drug delivery application. The DTC-loaded PLA-NPs were prepared by the single-nanoemulsification method using the poly(vinyl alcohol) (PVA) as a surfactant. The nanostructured system was characterized mainly by dynamic light scattering (DLS), electrophoretic light scattering (ELS), and transmission electron microscopy (TEM). The NPs show good colloidal stability exhibiting mean hydrodynamic diameter 157 ± 5 nm and zeta potential − 36 ± 3 mV. The encapsulation efficiency and drug loading were 52 ± 14% and 4.8 ± 1.5%, respectively. The quantifications of DTC and residual PVA in the NPs were performed by UV-Vis absorption spectroscopy. The analytical methods were validated according to regulatory agencies. Both quantification analytical curves showed good precision, in repeatability (intra-day) and intermediate (inter-day), and also good accuracy with low values of detection and quantification. The new nanostructured system, DTC-loaded PLA-NPs, shows advantages to improve stability and to overcome water solubility problems of the dithiocarbazate Schiff bases aiming potential drug delivery applications.

    更新日期:2019-11-01
  • Designing the poly[1,5-bis( N -pyrrolyl)pentane as a new horizon of polypyrrole paradigm with its structural and optical highlights
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2019-10-30
    Zahoor Ahmad, Saadia Bibi, Sanum Mushtaq, Clare Hoskins, Muhammad Arshad, Tashfeen Akhtar

    Poly[1,5-bis(N-pyrrolyl)pentane] (PBNPP) has been designed as a new addition to the modified polypyrrole family. This study entails the introduction of a pentane spacer between two pyrrole moieties and subsequently their oxidative polymerization under ambient conditions. The newly designed monomer and its polymer were fully characterized by FT-IR. The structural and optical behaviors were comparatively explored with reference to polypyrrole (Ppy), which was again prepared under same conditions. SEM was employed to visualize the morphology of PBNPP and Ppy comparatively. The data demonstrated the morphology of the PBNPP as spherical beads with a greater extent of surface porosity compared to Ppy, which possesses a compact granular form. The structural parameters were explored by XRD, where both possess crystallites of smaller size. Thermal behaviors were analyzed by TGA and DSC, where the newly designed polymer showed greater thermal stability and more plasticizing trend as compared to Ppy. Optical and HOMO-LUMO attributes have been characterized using UV-Vis spectrophotometer and diffused reflectance spectroscopy (DRS). The PBNPP demonstrated greater molar absorption and lesser HOMO-LUMO gap as compared to Ppy. The PBNPP was proposed as a suitable candidate for photoconductivity compared with the Ppy. Thus, the polymer produced from the modified pyrrole is thermally more stable, has high plasticizing character, reflects greater optically sensitivity, and possesses ease of electronic transition compared to its counterpart.

    更新日期:2019-11-01
  • Solvent induced phenomena in a dendronized linear polymer.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2013-12-03
    Anja Kroeger,Baozhong Zhang,Christine Rosenauer,A Dieter Schlüter,Gerhard Wegner

    The properties of a dendronized linear polymer (DP) in dilute solutions depending on solvent quality and temperature are described. The polymer has a contour length of Lc = 1,060 nm. The sample of the fourth generation (PG4) was analyzed in the thermodynamically good solvents dioxane, chloroform, and methanol. The wormlike macromolecule has a persistence length lp = 7 nm in dioxane and a cross-section radius determined by small angle X-ray scattering (SAXS) of Rc (SAXS) = 2.8 nm. The bulk density of PG4 determined by SAXS was compared with solution density. Evidence for substantial swelling of the cross-section was found. Toluene acts as a thermodynamically poor solvent (θ solvent). Above the θ temperature Tθ , a strong temperature dependence of the size and the Young's modulus E was observed. Following Odijk, E/kBT ∼1 was found. Below Tθ , a regime characterized by unswelling of the wormlike chains was observed. The results suggest that DPs can be described as soft colloid filaments, which are subject to commonly observed interactions in colloidal systems. A phase diagram indicates a regime below Tθ in which fluctuations of osmotic pressure inside the filaments result in periodic undulation of the chains. In summary, introducing a dense dendritic shell around the backbone converts conventional polymers into molecular colloids. Figureᅟ

    更新日期:2019-11-01
  • Preparation, structural, and optical features of two-dimensional cross-linked DNA/gold-nanoparticle conjugates.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2006-01-01
    Michael Noyong,Buelent Ceyhan,Christof M Niemeyer,Ulrich Simon

    The formation and the optical features of two-dimensional aggregates formed by DNA-directed immobilization and cross-linking of bifunctional DNA-gold nanoparticles at flat gold substrates are analyzed. The samples are structurally characterized by atomic force microscopy to evaluate the particle size, the particle densities, and the degree of aggregation. The optical characteristics determined by UV/visible measurements are correlated with the structural features observed.

    更新日期:2019-11-01
  • Future challenges in colloid and interfacial science.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2010-01-26
    Helmuth Möhwald

    This article deals with topics where I expect special future challenges, exemplifying these by experiments out of my own department. One area where I expect large progress also in view of many technical developments in the past concerns the understanding of the structure of fluid interfaces at the atomic level. It is shown by non-linear optical spectroscopies that the free water surface is ice-like and can be "liquefied" by ion adsorption. X-ray fluorescence from the interface demonstrates that ion binding is very specific which cannot be explained by existing theories. A second major area are nonequilibrium features, and one of the old and new ones here is nucleation and growth. This presentation concentrates on effects produced by ultrasound, a well-defined trigger of gas bubble formation. It exhibits high potential for chemistry at extreme conditions but with a reactor at normal conditions. It has special importance for treatment of surfaces that can be also manipulated via controlled surface energies. A third area will concern complex and smart systems with multiple functions in materials and biosciences. As next generation, I anticipate those with feedback control, and examples on this are self-repairing coatings.

    更新日期:2019-11-01
  • The temperature effect on electrokinetic properties of the silica-polyvinyl alcohol (PVA) system.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2011-04-08
    Małgorzata Wiśniewska

    The influence of polyvinyl alcohol (PVA) adsorption on the structure of the diffuse layer of silica (SiO(2)) in the temperature range 15-35 °C was examined. The microelectrophoresis method was used in the experiments to determine the zeta potential of the solid particles in the absence and presence of the polymer. The adsorption of PVA macromolecules causes the zeta potential decrease in all investigated SiO(2) systems. Moreover this, decrease is the most pronounced at the highest examined temperature. Obtained results indicate that the conformational changes of adsorbed polymer chains are responsible for changes in electrokinetic properties of silica particles. Moreover, the structure of diffuse layer on the solid surface with adsorbed polymer results from the following effects: the presence of acetate groups in PVA chains, the blockade of silica surface groups by adsorbed polymer and the shift of slipping plane due to macromolecules adsorption.

    更新日期:2019-11-01
  • Ferritin immobilization on patterned poly(2-hydroxyethyl methacrylate) brushes on silicon surfaces from colloid system.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2011-04-05
    Tsung-Yen Chen,Jem-Kun Chen

    In this paper, we describe a graft polymerization/solvent immersion method for generating poly(2-hydroxyethyl methacrylate) (PHEMA) brushes in various patterns. We used a novel fabrication process, involving very-large-scale integration and oxygen plasma treatment, to generate well-defined patterns of polymerized PHEMA on patterned Si(100) surfaces. We observed brush- and mushroom-like regions for the PHEMA brushes, with various pattern resolutions, after immersing wafers presenting lines of these polymers in MeOH and n-hexane, respectively. The interaction between PHEMA and ferritin protein sheaths in MeOH and n-hexane (good and poor solvent for PHEMA, respectively) was used to capture and release ferritins from fluidic system. The "tentacles" behaver for PHEMA brushes was found through various solvents in fluidic system. Using high-resolution scanning electron microscopy, we observed patterned ferritin Fe cores on the Si surface after pyrolysis of the patterned PHEMA brushes and ferritin protein sheaths, which verify the "tentacles" behaver for PHEMA brushes.

    更新日期:2019-11-01
  • Synthesis and Physicochemical Properties of Cationic Microgels Based on Poly(N-isopropylmethacrylamide).
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2011-03-23
    Xiaobo Hu,Zhen Tong,L Andrew Lyon

    Surfactant-free, radical precipitation co-polymerization of N-isopropylmethacrylamide (NIPMAm) and the cationic co-monomer N-(3-aminopropyl) methacrylamide hydrochloride (APMH) was carried out to prepare microgels functionalized with primary amines. The morphology and hydrodynamic diameter of the microgels were characterized by atomic force microscopy (AFM) and photon correlation spectroscopy (PCS), with the effect of NaCl concentration and initiator type on the microgel size and yield being investigated. When a V50-initiated reaction was carried out in pure water, relatively small microgels (~160 nm diameter) were obtained in low yield (~20%). However, both the yield and size increased if the reaction was carried out in saline or by using APS as initiator instead of V50. Stable amine-laden microgels in the range from 160 nm to 950 nm in diameter with narrow size distributions were thus produced using reaction media with controlled salinity. Microgel swelling and electrophoretic mobility values as a function of pH, ionic strength and temperature were also studied, illustrating the presence of cationic sidechains and their influence on microgel properties. Finally, the availability of the primary amine groups for post-polymerization modification was confirmed via modification with fluorescein-NHS.

    更新日期:2019-11-01
  • Properties of small molecular drug loading and diffusion in a fluorinated PEG hydrogel studied by H molecular diffusion NMR and F spin diffusion NMR.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2010-12-21
    Errol V Mathias,Julia Aponte,Julia A Kornfield,Yong Ba

    R(f)-PEG (fluoroalkyl double-ended poly(ethylene glycol)) hydrogel is potentially useful as a drug delivery depot due to its advanced properties of sol-gel two-phase coexistence and low surface erosion. In this study, (1)H molecular diffusion nuclear magnetic resonance (NMR) and (19)F spin diffusion NMR were used to probe the drug loading and diffusion properties of the R(f)-PEG hydrogel for small anticancer drugs, 5-fluorouracil (FU) and its hydrophobic analog, 1,3-dimethyl-5-fluorouracil (DMFU). It was found that FU has a larger apparent diffusion coefficient than that of DMFU, and the diffusion of the latter was more hindered. The result of (19)F spin diffusion NMR for the corresponding freeze-dried samples indicates that a larger portion of DMFU resided in the R(f) core/IPDU intermediate-layer region (where IPDU refers to isophorone diurethane, as a linker to interconnect the R(f) group and the PEG chain) than that of FU while the opposite is true in the PEG-water phase. To understand the experimental data, a diffusion model was proposed to include: (1) hindered diffusion of the drug molecules in the R(f) core/IPDU-intermediate-layer region; (2) relatively free diffusion of the drug molecules in the PEG-water phase (or region); and (3) diffusive exchange of the probe molecules between the above two regions. This study also shows that molecular diffusion NMR combined with spin diffusion NMR is useful in studying the drug loading and diffusion properties in hydrogels for the purpose of drug delivery applications.

    更新日期:2019-11-01
  • Grafted ionomer complexes and their effect on protein adsorption on silica and polysulfone surfaces.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2010-12-03
    Agata M Brzozowska,Arie de Keizer,Christophe Detrembleur,Martien A Cohen Stuart,Willem Norde

    We have studied the formation and the stability of ionomer complexes from grafted copolymers (GICs) in solution and the influence of GIC coatings on the adsorption of the proteins β-lactoglobulin (β-lac), bovine serum albumin (BSA), and lysozyme (Lsz) on silica and polysulfone. The GICs consist of the grafted copolymer PAA(28)-co-PAPEO(22) {poly(acrylic acid)-co-poly[acrylate methoxy poly(ethylene oxide)]} with negatively charged AA and neutral APEO groups, and the positively charged homopolymers: P2MVPI(43) [poly(N-methyl 2-vinyl pyridinium iodide)] and PAH∙HCl(160) [poly(allylamine hydrochloride)]. In solution, these aggregates are characterized by means of dynamic and static light scattering. They appear to be assemblies with hydrodynamic radii of 8 nm (GIC-PAPEO(22)/P2MVPI(43)) and 22 nm (GIC-PAPEO(22)/PAH∙HCl(160)), respectively. The GICs partly disintegrate in solution at salt concentrations above 10 mM NaCl. Adsorption of GICs and proteins has been studied with fixed angle optical reflectometry at salt concentrations ranging from 1 to 50 mM NaCl. Adsorption of GICs results in high density PEO side chains on the surface. Higher densities were obtained for GICs consisting of PAH∙HCl(160) (1.6 ÷ 1.9 chains/nm(2)) than of P2MVPI(43) (0.6 ÷ 1.5 chains/nm(2)). Both GIC coatings strongly suppress adsorption of all proteins on silica (>90%); however, reduction of protein adsorption on polysulfone depends on the composition of the coating and the type of protein. We observed a moderate reduction of β-lac and Lsz adsorption (>60%). Adsorption of BSA on the GIC-PAPEO(22)/P2MVPI(43) coating is moderately reduced, but on the GIC-PAPEO(22)/PAH∙HCl(160) coating it is enhanced.

    更新日期:2019-11-01
  • Synthesis and characterisation of coating polyurethane cationomers containing fluorine built-in hard urethane segments.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2010-10-12
    Bożena Król,Piotr Król,Stanisław Pikus,Paweł Chmielarz,Krzysztof Skrzypiec

    Polyurethane cationomers were synthesised in the reaction of 4,4'-methylenebis(phenyl isocyanate) with polyoxyethylene glycol (M = 2,000) or poly(tetrafluoroethyleneoxide-co-difluoromethylene oxide) α,ω-diisocyanate and N-methyl diethanolamine. Amine segments were built-in to the urethane-isocyanate prepolymer in the reaction with 1-bromobutane or formic acid, and then they were converted to alkylammonium cations. The obtained isocyanate prepolymers were then extended in the aqueous medium that yielded stable aqueous dispersions which were applied on the surfaces of test poly(tetrafluoroethylene) plates. After evaporation of water, the dispersions formed thin polymer coatings. (1)H, (13)C NMR and IR spectral methods were employed to confirm chemical structures of synthesised cationomers. Based on (1)H NMR and IR spectra, the factors κ and α were calculated, which represented the polarity level of the obtained cationomers. The DSC, wide angle X-ray scattering and atom force microscopy methods were employed for the microstructural assessment of the obtained materials. Changes were discussed in the surface free energy and its components, as calculated independently according to the method suggested by van Oss-Good, in relation to chemical and physical structures of cationomers as well as morphology of coating surfaces obtained from those cationomers. Fluorine incorporated into cationomers (about 30%) contributed to lower surface free energy values, down to about 15 mJ/m(2). That was caused by gradual weakening of long-range interactions within which the highest share is taken by dispersion interactions.

    更新日期:2019-11-01
  • Grafted block complex coacervate core micelles and their effect on protein adsorption on silica and polystyrene.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2010-07-31
    Agata M Brzozowska,Arie de Keizer,Willem Norde,Christophe Detrembleur,Martien A Cohen Stuart

    We have studied the formation and the stability of grafted block complex coacervate core micelles (C3Ms) in solution and the influence of grafted block C3M coatings on the adsorption of the proteins beta-lactoglobulin, bovine serum albumin, and lysozyme. The C3Ms consist of a grafted block copolymer PAA(21)-b-PAPEO(14) (poly(acrylic acid)-b-poly(acrylate methoxy poly(ethylene oxide)), with a negatively charged PAA block and a neutral PAPEO block and a positively charged homopolymer P2MVPI (poly(N-methyl 2-vinyl pyridinium iodide). In solution, these C3Ms partly disintegrate at salt concentrations between 50 and 100 mM NaCl. Adsorption of C3Ms and proteins has been studied with fixed-angle optical reflectometry, at salt concentrations ranging from 1 to 100 mM NaCl. In comparison with the adsorption of PAA(21)-b-PAPEO(14) alone adsorption of C3Ms significantly increases the amount of PAA(21)-b-PAPEO(14) on the surface. This results in a higher surface density of PEO chains. The stability of the C3M coatings and their influence on protein adsorption are determined by the composition and the stability of the C3Ms in solution. A C3M-PAPEO(14)/P2MVPI(43) coating strongly suppresses the adsorption of all proteins on silica and polystyrene. The reduction of protein adsorption is the highest at 100 mM NaCl (>90%). The adsorbed C3M-PAPEO(14)/P2MVPI(43) layer is partly removed from the surface upon exposure to an excess of beta-lactoglobulin solution, due to formation of soluble aggregates consisting of beta-lactoglobulin and P2MVPI(43). In contrast, C3M-PAPEO(14)/P2MVPI(228) which has a fivefold longer cationic block enhances adsorption of the negatively charged proteins on both surfaces at salt concentrations above 1 mM NaCl. A single PAA(21)-b-PAPEO(14) layer causes only a moderate reduction of protein adsorption.

    更新日期:2019-11-01
  • Polyamide capsules via soft templating with oil drops-1. Morphological studies of the capsule wall.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2010-01-26
    Hisham Essawy,Klaus Tauer

    Poly(terephthalamide) microcapsules can be reproducibly and easily prepared by interfacial polycondensation around emulsion droplets in water. Oil drops of cyclohexane/chloroform mixture stabilized with poly(vinyl alcohol) containing terephthaloylchloride serve as soft template. The interfacial polycondensation starts immediately after addition of an amine mixture (hexamethylenediamine/diethylenetriamine). Light and scanning electron microscopy prove the formation of capsules with size distribution in the range from a few up to 100 microm depending on particular composition of the reaction mixture. The morphology of the capsule wall is characterized by precipitated particles. If instead of pure organic solvents a reactive oil phase is used as template, the capsules can serve in subsequent reactions as templates for the synthesis of composite particles. In this way, styrene can be radically polymerized inside the capsule leading to composite capsules. The capsule morphology is determined by the partition of all components between all phases.

    更新日期:2019-11-01
  • Synthesis of phosphonate-functionalized polystyrene and poly(methyl methacrylate) particles and their kinetic behavior in miniemulsion polymerization.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2009-10-24
    Anke Ziegler,Katharina Landfester,Anna Musyanovych

    Phosphonate-functionalized polymer nanoparticles were synthesized by free-radical copolymerization of vinylphosphonic acid (VPA) with styrene or methyl methacrylate (MMA) using the miniemulsion technique. The influence of different parameters such as monomer and surfactant type, amount of vinylphosphonic acid on the average particle size, and size distribution was studied using dynamic light scattering and transmission electron microscopy. Depending on the amount and type of the surfactant used (ionic or non-ionic), phosphonate-functionalized particles in a size range from 102 to 312 nm can be obtained. The density of the phosphonate groups on the particle surface was higher in the case of using MMA as a basis monomer than polystyrene. The kinetic behavior of VPA copolymerization with styrene or MMA using a hydrophobic initiator was investigated by reaction calorimetry. Different kinetic curves were observed for miniemulsion (co)polymerization of styrene- and MMA-based nanoparticles indicating different nucleation mechanisms.

    更新日期:2019-11-01
  • Interaction of cylindrical polymer brushes in dilute and semi-dilute solution.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2009-10-10
    Sreenath Bolisetty,Sabine Rosenfeldt,Christophe N Rochette,Ludger Harnau,Peter Lindner,Youyong Xu,Axel H E Müller,Matthias Ballauff

    We present a systematic study of flexible cylindrical brush-shaped macromolecules in a good solvent by small-angle neutron scattering (SANS), static light scattering (SLS), and by dynamic light scattering (DLS) in dilute and semi-dilute solution. The SLS and SANS data extrapolated to infinite dilution lead to the shape of the polymer that can be modeled in terms of a worm-like chain with a contour length of 380 nm and a persistence length of 17.5 nm. SANS data taken at higher polymer concentration were evaluated by using the polymer reference interaction site model (PRISM). We find that the persistence length reduce from 17.5 nm at infinite dilution to 5.3 nm at the highest concentration (volume fraction 0.038). This is comparable with the decrease of the persistence length in semi-dilute concentration predicted theoretically for polyelectrolytes. This finding reveals a softening of stiffness of the polymer brushes caused by their mutual interaction.

    更新日期:2019-11-01
  • Templating hydrogels.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2009-10-10
    John Texter

    Templating processes for creating polymerized hydrogels are reviewed. The use of contact photonic crystals and of non-contact colloidal crystalline arrays as templates are described and applications to chemical sensing and device fabrication are illustrated. Emulsion templating is illustrated in the formation of microporous membranes, and templating on reverse emulsions and double emulsions is described. Templating in solutions of macromolecules and micelles is discussed and then various applications of hydrogel templating on surfactant liquid crystalline mesophases are illustrated, including a nanoscale analogue of colloidal crystalline array templating, except that the bead array in this case is a cubic array of nonionic micelles. The use of particles as templates in making core-shell and hollow microgel beads is described, as is the use of membrane pores as another illustration of confinement templating.

    更新日期:2019-11-01
  • Miscibility of sodium chloride and sodium dodecyl sulfate in the adsorbed film and aggregate.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2009-10-10
    Hidemi Iyota,Rumen Krastev

    The adsorption, micelle formation, and salting out of sodium dodecyl sulfate in the presence of sodium chloride were studied from the viewpoint of their mixed adsorption and aggregate formation. The surface tension of aqueous solutions of a sodium chloride-sodium dodecyl sulfate mixture was measured as a function of the total molality and composition of the mixture. Phase diagrams of adsorption and aggregate formation were obtained by applying thermodynamic equations to the surface tension. Judging from the phase diagrams, sodium chloride and sodium dodecyl sulfate are miscible in the adsorbed film at very large composition of sodium chloride and in the salted-out crystalline particle, while they are immiscible in the micelle. The miscibilities in the adsorbed film, micelle, and crystalline particle increase in the following order: particle > adsorbed film > micelle. The difference in miscibility among the oriented states was ascribed to the difference in geometry between the adsorbed film and micelle and to the interaction between bilayer surfaces in the particle.

    更新日期:2019-11-01
  • Towards a consistent mechanism of emulsion polymerization-new experimental details.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2008-05-01
    Klaus Tauer,Hugo Hernandez,Steffen Kozempel,Olga Lazareva,Pantea Nazaran

    The application of atypical experimental methods such as conductivity measurements, optical microscopy, and nonstirred polymerizations to investigations of the 'classical' batch ab initio emulsion polymerization of styrene revealed astonishing facts. The most important result is the discovery of spontaneous emulsification leading to monomer droplets even in the quiescent styrene in water system. These monomer droplets with a size between a few and some hundreds of nanometers, which are formed by spontaneous emulsification as soon as styrene and water are brought into contact, have a strong influence on the particle nucleation, the particle morphology, and the swelling of the particles. Experimental results confirm that micelles of low-molecular-weight surfactants are not a major locus of particle nucleation. Brownian dynamics simulations show that the capture of matter by the particles strongly depends on the polymer volume fraction and the size of the captured species (primary free radicals, oligomers, single monomer molecules, or clusters).

    更新日期:2019-11-01
  • Performance of a fast fiber based UV/Vis multiwavelength detector for the analytical ultracentrifuge.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2008-02-01
    Holger M Strauss,Engin Karabudak,Saroj Bhattacharyya,Andreas Kretzschmar,Wendel Wohlleben,Helmut Cölfen

    The optical setup and the performance of a prototype UV/Vis multiwavelength analytical ultracentrifuge (MWL-AUC) is described and compared to the commercially available Optima XL-A from Beckman Coulter. Slight modifications have been made to the optical path of the MWL-AUC. With respect to wavelength accuracy and radial resolution, the new MWL-AUC is found to be comparable to the existing XL-A. Absorbance accuracy is dependent on the light intensity available at the detection wavelength as well as the intrinsic noise of the data. Measurements from single flashes of light are more noisy for the MWL-AUC, potentially due to the absence of flash-to-flash normalization in the current design. However, the possibility of both wavelength and scan averaging can compensate for this and still give much faster scan rates than the XL-A. Some further improvements of the existing design are suggested based on these findings.

    更新日期:2019-11-01
  • Synthesis of Multifunctional Nanogels Using a Protected Macromonomer Approach.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2008-12-17
    Neetu Singh,L Andrew Lyon

    Nanoparticles possessing multiple functionalities provide synthetic handles for varied surface chemistries, making them useful for a range of applications such as biotargeting and drug delivery. However, the combination of interfering functionalities on the same particle is often challenging. We have employed a synthetic scheme involving chemical protection/deprotection to combine interfering functional groups on the same hydrogel nanoparticle. The synthesis of amine-containing poly(N-isopropylacrylamide) nanogels was carried out via free radical precipitation polymerization by incorporating a Fmoc-protected amine PEG macromonomer. The Fmoc group was then removed to obtain free amines, which were shown to be available for conjugation. We further explored pNIPAm-co-acrylic acid nanogels with a protected amine-PEG, yielding zwitterionic particles. With careful attention to the order of the chemoligation and deprotection steps, these interfering functional groups can be forced to behave in a pseudo-orthogonal fashion, allowing for multiple chemoligation steps that employ both the amine and carboxylic acid groups.

    更新日期:2019-11-01
  • Size Controlled Synthesis of Monodispersed, Core/Shell Nanogels.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2008-09-05
    William H Blackburn,L Andrew Lyon

    Small, monodispersed nanogels (~ 50-nm radius) were synthesized by free-radical precipitation polymerization and characterized using a suite of light scattering and chromatography methods. Nanogels were synthesized with either N-isopropylacrylamide or N-isopropylmethacrylamide as the main monomer, with acrylic acid or 4-acrylamidofluorescein as a co-monomer and N, N'-methylenebis(acrylamide) as a cross-linker. By varying the surfactant and initiator concentrations, particle size was controlled while maintaining excellent monodispersity. An amine-containing shell was added to these core particles to facilitate subsequent bioconjugation. Successful conjugation of folic acid to the particles was demonstrated as an example of how such materials might be employed in a targeted drug delivery system.

    更新日期:2019-11-01
  • Modelling the surface free energy parameters of polyurethane coats-part 2. Waterborne coats obtained from cationomer polyurethanes.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2014-05-13
    Piotr Król,Bożena Król,Jaromir B Lechowicz

    Polyurethane cationomer coats were synthesised on the basis of typical diisocyanates, properly selected polyether polyols, HO-tertiary amines and HCOOH as quaternisation reagents. The values of their surface free energy (SFE) parameters were obtained by the van Oss-Good method, with the use of the contact angle values which had been found by the goniometric method. Based on the obtained findings, empirical models were developed which made it possible to anticipate the effects of the raw material types on the SFE values of the produced coats. The possibility was noted to adjust the SFE values within 25-50 mJ/m2 by selecting carefully suitable parent substances. The principal consequences for the formation of improved hydrophobicity coats, applicable inter alia specialised protective coatings, were found to come not only from diisocyanate and polyol types but also from the alkylammonium cation structure which results from the use of different tertiary amines. The fundamental SFE lowering effect was noted when tertiary amines with 0-15 % of the 2,2,3,3-tetrafluoro-1,4-butanediol as a fluorinated chain extender was incorporated into polymer chains.

    更新日期:2019-11-01
  • Improvement of thermal stability of polypropylene using DOPO-immobilized silica nanoparticles.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2012-09-01
    Quanxiao Dong,Yanfen Ding,Bin Wen,Feng Wang,Huicong Dong,Shimin Zhang,Tongxin Wang,Mingshu Yang

    After the surface silylation with 3-methacryloxypropyltrimethoxysilane, silica nanoparticles were further modified by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The immobilization of DOPO on silica nanoparticles was confirmed by Fourier transform infrared spectroscopy, UV-visible spectroscopy, magic angle spinning nuclear magnetic resonance, and thermogravimetric analysis. By incorporating the DOPO-immobilized silica nanoparticles (5 wt%) into polypropylene matrix, the thermal oxidative stability exhibited an improvement of 62 °C for the half weight loss temperature, while that was only 26 °C increment with incorporation of virgin silica nanoparticles (5 wt%). Apparent activation energies of the polymer nanocomposites were estimated via Flynn-Wall-Ozawa method. It was found that the incorporation of DOPO-immobilized silica nanoparticles improved activation energies of the degradation reaction. Based on the results, it was speculated that DOPO-immobilized silica nanoparticles could inhibit the degradation of polypropylene and catalyze the formation of carbonaceous char on the surface. Thus, thermal stability was significantly improved.

    更新日期:2019-11-01
  • Comparison of adsorption affinity of polyacrylic acid for surfaces of mixed silica-alumina.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2014-03-13
    Małgorzata Wiśniewska,Teresa Urban,Elżbieta Grządka,Vladimir I Zarko,Vladimir M Gun'ko

    The influence of solution pH (in the range 3-9) on the adsorption of polyacrylic acid (PAA) on the mixed silica-alumina surface (SA-3: SiO2 97 %-Al2O3 3 % and SA-96: SiO2 4 %-Al2O3 96 %) was investigated. The following methods were applied in experiments: spectrophotometry, viscosimetry, potentiometric titration, and microelectrophoresis, which enable determination of adsorbed amount of the polymer, thickness of its adsorption layers, surface charge density, and zeta potential of solid particles in the presence and absence of PAA, respectively. The obtained results indicate that rise of solution pH causes the decrease of PAA adsorption and the increase of its adsorption layer thickness on surfaces of both solids. Moreover, significantly higher adsorption of polyacrylic acid was obtained on the SA-96 surface. This is a result of more favorable electrostatic interactions occurring between the adsorbing polymer chains and the SA-96 surface and formation of a greater number of adsorbate-adsorbent connections through hydrogen bridges.

    更新日期:2019-11-01
  • A new approach to decoupling of bacterial adhesion energies measured by AFM into specific and nonspecific components.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2014-02-25
    Asma O Eskhan,Nehal I Abu-Lail

    A new method to decoupling of bacterial interactions measured by atomic force microscopy (AFM) into specific and nonspecific components is proposed. The new method is based on computing the areas under the approach and retraction curves. To test the efficacy of the new method, AFM was used to probe the repulsion and adhesion energies present between L. monocytogenes cells cultured at five pH values (5, 6, 7, 8 and 9) and silicon nitride (Si3N4). Overall adhesion energy was then decoupled into its specific and nonspecific components using the new method as well as using Poisson statistical approach. Poisson statistical method represents the most commonly used approach to decouple bacterial interactions into their components. For all pH conditions investigated, specific energies dominated the adhesion and a transition in adhesion and repulsion energies for cells cultured at pH 7 was observed. When compared, the differences in the specific and nonspecific energies obtained using Poisson analysis and the new method were on average 2.2% and 6.7%, respectively. The relatively close energies obtained using the two approaches demonstrate the efficacy of the new method as an alternative way to decouple adhesion energies into their specific and nonspecific components.

    更新日期:2019-11-01
  • Influence of crosslinker and ionic comonomer concentration on glass transition and demixing/mixing transition of copolymers poly(N-isopropylacrylamide) and poly(sodium acrylate) hydrogels.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2014-02-11
    Iwona Zarzyka,Marek Pyda,Maria Laura Di Lorenzo

    Hydrogels based on N-isopropylacrylamide and sodium acrylate as ionic comonomer were synthesized by free radical polymerization in water using N,N'-methylenebisacrylamide as crosslinker and ammonium persulfate as initiator. The glass transition of dried copolymers poly(N-isopropylacrylamide) (PNIPA) and poly(sodium acrylate) (SA) gels and demixing/mixing transition of PNIPA-SA hydrogels swollen with increasing amounts of water were studied using conventional differential scanning calorimetry. In the crosslinked polymers, the glass transition linearly increases, and the transition range becomes broader, with increasing crosslinker content. Increasing content of ionic comonomer also produces an increase of glass transition temperature, which moves to higher temperatures with higher sodium acrylate fraction. The influence of chemical structure of PNIPA-SA hydrogels on the lower critical solution temperature (LCST) of PNIPA-SA/water mixtures during heating and cooling was quantified as function of the content of the crosslinker and the ionic comonomer, as well as water content of the hydrogel in the range from 95 to 70 wt%. At parity of water content, the LCST occurs at higher temperatures for gels containing higher amounts of sodium acrylate. Similarly, the introduction of N,N'-methylenebisacrylamide causes an increase of the LCST, which grows with increasing of crosslinking degree of the hydrogel.

    更新日期:2019-11-01
  • Soap-free emulsion polymerization of poly (methyl methacrylate-co-butyl acrylate): effects of anionic comonomers and methanol on the different characteristics of the latexes.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2014-01-15
    Hossein Adelnia,Saeed Pourmahdian

    Soap-free emulsion polymerization (SFEP) of methyl methacrylate, butyl acrylate was conducted in water/methanol media with sodium salts of four different acidic comonomers, namely styrene sulfonic acid (NaSS), 2-acrylamide-2-methyl-1-propane sulfonic acid (NaAmps), acrylic acid (NaAA), and itaconic acid (Na2ita). It was found that the introduction of methanol as co-solvent (35 wt%) to the medium greatly decreases the amount of water-soluble polyelectrolyte in the cases NaAA and Na2ita while it does not make difference for NaSS and NaAmps. Having employed the concept of conductance dependency to the ion mobility, the onset concentration in which soluble chains were formed was detected. The addition of sulfonic-based comonomers (NaSS and NaAmps), first decreased particle size and then led to predomination of solution polymerization over SFEP. On the contrary, the incorporation of carboxylic-based comonomers (NaAA and Na2ita) led to increase in particle size. Moreover, the particle size results were in good qualitative agreement with the classical Smith-Ewart theory.

    更新日期:2019-11-01
  • A new, simple, green, and one-pot four-component synthesis of bare and poly(α,γ, L-glutamic acid)-capped silver nanoparticles.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2012-02-01
    Magdalena Stevanović,Igor Savanović,Vuk Uskoković,Srečo D Skapin,Ines Bračko,Uroš Jovanović,Dragan Uskoković

    A simple and green chemical method has been developed to synthesize stable bare and capped silver nanoparticles based on the reduction of silver ions by glucose and capping by poly(α,γ,L-glutamic acid) (PGA). The use of ammonia during synthesis was avoided. PGA has had a dual role in the synthesis and was used as a capping agent to make the silver nanoparticle more biocompatible and to protect the nanoparticles from agglomerating in the liquid medium. The synthesized PGA-capped silver nanoparticles in the size range 5-45 nm were stable over long periods of time, without signs of precipitation. Morphological examination has shown that the silver nanoparticles had a nearly spherical, multiply twinned structure. The effects of the reaction temperature and the reaction time during the synthesis were investigated too. The biocompatibility of the PGA-capped silver nano-particles is discussed in terms of in vitro toxicity with human intestinal Caco-2 cells. The samples were characterized by UV-Visible spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurements.

    更新日期:2019-11-01
  • Controllable immobilization of polyacrylamide onto glass slide: synthesis and characterization.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2013-09-24
    Linghan Xiao,Xin Zheng,Tianyi Zhao,Liying Sun,Fengqi Liu,Ge Gao,Alideertu Dong

    A novel route was introduced to synthesize dense polyacrylamide (PAM) onto the glass slide surface. To investigate the surface chemistry of the PAM on the glass slides, X-ray photoelectron spectroscopy (XPS) was utilized to obtain detailed chemical state information on the PAM layer constituents. The XPS peak data were consistent with the presented model of the PAM on the glass slide surface. Scanning electron microscopy and atomic force microscope data indicated the presence of PAM on the glass slides, which consist of nodules. The results showed that PAM was successfully immobilized onto glass slides with a two-tier structure under aqueous condition and a monolayer structure under anhydrous condition. Compared with those under aqueous condition, the controllability of the molecular layer on glass slides and the reproducibility under anhydrous condition were much better, which makes anhydrous condition an advisable condition for the study of the reaction mechanisms of glass slides modified by PAM.

    更新日期:2019-11-01
  • Control on shape, porosity and surface hydrophilicity of hematite particles by using polymers.
    Colloid. Polym. Sci. (IF 1.906) Pub Date : 2006-01-01
    Kazuhiko Kandori,Natsuko Hori,Tatsuo Ishikawa

    The shape, porosity, and surface hydrophilicity of hematite particles formed from a forced hydrolysis reaction of acidic FeCl3 solution were controlled by using a trace of polymers (0.001 and 0.003 wt%). The spherical particles were produced on the systems with polyvinyl alcohol (PVA) and polyaspartic acid (PAS). In the case of polyacryl amide (PAAm), slightly small spherical particles were precipitated at 0.003 wt%. However, polyacrylic acid (PAAc) and poly-γ-glutamic acid (PGA) gave ellipsoidal particles. This morphological change on hematite particles depended on the order of functional groups of polymers as -OH<-CONH2<-COOH<-COOH and ⟩C=O, corresponding to the order in extent of polymer molecules for complexation to Fe3+ ions and adsorption onto particle surface. Accompanying this order, the hematite particles produced were changed from less porous to microporous. On the other hand, only the system with 0.003 wt% of PAAm produced mesoporous hematite particles. Choosing the kinds of polymers also controlled the ultramicroporosity and surface hydrophilicity of the particles.

    更新日期:2019-11-01
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
2020新春特辑
限时免费阅读临床医学内容
ACS材料视界
科学报告最新纳米科学与技术研究
清华大学化学系段昊泓
自然科研论文编辑服务
加州大学洛杉矶分校
上海纽约大学William Glover
南开大学化学院周其林
课题组网站
X-MOL
北京大学分子工程苏南研究院
华东师范大学分子机器及功能材料
中山大学化学工程与技术学院
试剂库存
天合科研
down
wechat
bug