When a polymer is used together with others, its aging process will be affected by the adjacent polymers. This infectious behavior between polymers makes the aging process more complex than that of an individual material. In this study, infectious behavior in photo-oxidation of polymers was investigated. Polypropylenes (PPs), an unstabilized PP and a commercial PP, were chosen as the infection sources. Six typical polymers, high density polyethylene (HDPE), low density polyethylene (LDPE), polystyrene (PS), polycarbonate (PC), poly(ethylene terephthalate) (PET), and polyamide 6 (PA6), were used as the targets. The degree of oxidation of the targets was evaluated by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). An accelerating effect of two infection sources on the photo-oxidation of the target polymers was observed. Potential infectious agents from the infection sources were detected by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and gas chromatography (GC). The acceleration effect of two main infectious agents, i.e. acetone and acetic acid, on the photo-oxidation of the commercial PP was verified. The infectious effect of the infection source on the target polymer was considered to be a comprehensive result of the effects of a variety of infectious agents.

Abstract In combination with methyllithium, a 2,6-bis(amino)phenol zinc complex 1 was used in the ring-opening polymerization of δ-valerolactone in the absence or presence of benzyl alcohol and showed high efficiency, mainly producing cyclic and linear polyvalerolactones, respectively. On the basis of homopolymerization, the ring-opening copolymerization of ε-caprolactone and δ-valerolactone was investigated. The P(CL-co-VL) random copolymers, PCL-b-PVL and PVL-b-PCL diblock copolymers, were prepared by varying the feeding strategy (premixing or sequential feeding). The copolymer composition was adjusted by varying the feeding ratio of two monomers. The structure and thermal properties of obtained polymers were characterized by GPC, 1H-NMR, 13C-NMR, MALDI-TOF mass spectroscopy, and DSC, respectively.

Abstract A series of Diels-Alder reaction cross-linked thermosets with recyclability and healability were prepared from furan-containing aromatic polyamide and bismaleimides with different chemical structures. The structures of synthesized bismaleimides were confirmed by 1H nuclear magnetic resonance (1H-NMR) spectroscopy; their reversible cross-linking with the furanic polyamide was further detected by 1H-NMR technique and sol-gel transition behavior. The dynamic mechanical analysis and tensile test revealed the variable thermal and mechanical properties of thermosets cross-linked by different bismaleimides and with different molar ratios of maleimide group to furan group (Ima/fur). The tensile test also demonstrated that the better recyclability and solvent-assisted healability of thermosets cross-linked could be achieved by more flexible bismaleimides. This work is expected to provide valuable information for design of recyclable and healable high-performance thermosets with desired properties.

Abstract Phosphazene base, t-BuP2, was employed to catalyze the proton transfer polymerization (PTP) of 2-hydroxyethyl acrylate (HEA), and PTP was further combined with ring-opening polymerization (ROP) to exploit a new type of hybrid copolymerization. The studies on homopolymerization showed that t-BuP2 was a particularly efficient catalyst for the polymerization of HEA at room temperature, giving an excellent monomer conversion. Throughout the polymerization, transesterification reactions were unavoidable, which increased the randomness in the structures of the resulting polymers. The studies on copolymerization showed that t-BuP2 could simultaneously catalyze the hybrid copolymerization via the combination of PTP and ROP at 25 °C. During copolymerization, HEA not only provided hydroxyl groups to initiate the ROP of ε-caprolactone (CL) but also participated in the polymerization as a monomer for PTP. The copolymer composition was approximately equal to the feed ratio, demonstrating the possibility to adjust the polymeric structure by simply changing the monomer feed ratio. This copolymerization reaction provides a simple method for synthesizing degradable functional copolymers from commercially available materials. Hence, it is important not only in polymer chemistry but also in environmental and biomedical engineering.

Abstract In this study, the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide) (PDLA-b-PBS-b-PDLA) triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized, and the crystallization behaviors of the PDLA and PBS blocks are investigated. Although both the crystallization behaviors of PBS and PDLA blocks depend on composition, they exhibit different variations. For the PDLA block, its crystallization behaviors are mainly influenced by temperature and block length. The crystallization signals of PDLA block appear in the B-D 2–2 specimen, and these signals get enhanced with PDLA block length. The crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100 °C. Crystallizing at higher temperature, the crystallization rates increase at first and then decrease with block length. The crystallization rates decrease as elevating the crystallization temperature. The melting temperatures of PDLA blocks increase with block lengths and crystallization temperatures. For the PBS block, its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA block. The crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized, while the crystallization rates of the PBS block exhibit unique component dependence, and the highest rate is observed in the B-D 2–2 specimen. The Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher temperature. This investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.

Abstract In this work, the Hofmeister effects of nine kinds of anions at different concentrations on the lower critical solution temperature (LCST) of the macroporous thermo-responsive poly(N-isopropylacrylamide) grafted poly(vinyl alcohol) formaldehyde (PVF-g-PNIPAM) hydrogels are investigated with differential scanning calorimetry (DSC). Four kinds of anions with strong hydration, including CO32–, SO42–, S2O32–, and F–, and four kinds of anions with weak hydration, including Br–, NO3–, I–, and ClO4–, and Cl– as a medium anion are systematically studied and found to demonstrate the effects of the residual hydroxyl groups and network structure of PVF on the LCST values of PVF-g-PNIPAM hydrogels in comparison with that of neat PNIPAM. On the one hand, the existence of hydroxyl groups on PVF backbone promotes the solubility of grafted PNIPAM due to their hydrophilicity and hydrogen-bond interactions with water. On the other hand, the network structure of as-prepared samples restricts free movements of grafted PNIPAM chains, which results in the increase of LCST values. In addition, the difference of grafting percentage also influences the variation of LCST values of PVF-g-PNIPAM hydrogels under salt concentration.

Ethylene-propene copolymers have been synthesized by three C1-symmetric metallocene molecules (1, 2, and 3), having tert-butyl substituents on the Cp moiety, on the fluorenyl moiety, or on both moieties, and methylaluminoxane (MAO) at different polymerization temperatures and monomer concentrations. Copolymers were investigated by 13C-NMR, 1H-NMR, and SEC analyses. A relationship was found between [EEE]/[E] ratios and copolymer molar masses in each series: the higher the [EEE]/[E] ratio, the lower the copolymer molar mass. At parity of [EEE]/[E] ratio, copolymer molar mass follows the order 1 >> 3 > 2. Chain end group analysis reveals that copolymers mainly terminate when propene is the last inserted unit, confirming that it is the greater facility of Mt-P-E-poly(E-co-P) to terminate that influences the copolymer molar mass. Among the catalysts considered, catalyst 1, which gives syndiospecific polypropene, gives greater activities, comonomer incorporation, and molar masses. Catalyst 3, which gives isospecific polypropene, in copolymerization performs better than 2, having the same bridge, with respect to activities, ethylene content, and molar masses. The good performance of this catalyst arises from the not necessity of polymer chain to back skip when ethylene is the last inserted unit.

Mechanistic transformation approach has been widely applied in polymer synthesis due to its unique feature combining structurally different polymers prepared by different polymerization mechanisms. Reported methods for the formation of block and graft copolymers through mechanistic transformation involve almost all polymerizations modes. However, certain polymerization processes require extensive purification processes, which can be time-consuming and problematic. Recent developments on controlled/living polymerizations involving radical and cationic mechanisms with the ability to control molecular weight and functionality led to new pathways for mechanistic transformations. In this mini-review, we systematically discussed relevant advances in the field through three main titles namely (i) from radical to cationic mechanism, (ii) from cationic to radical mechanism, and (iii) application of specific catalyst systems for both radical and cationic polymerizations.

High-performance low-k and low-loss circuit materials are urgently needed in the field of microelectronics due to the upcoming Fifth-Generation Mobile Communications Technology (5G Technology). Herein, a facile design strategy for non-fluorinated intrinsic low-k and low-loss polyimides is reported by fully considering the secondary relaxation behaviors of the polymer chains. A new amorphous non-fluorinated polymer (TmBPPA) with a k value of 2.23 and a loss tangent lower than 3.94 × 10−3 at 104 Hz has been designed and synthesized, which to the best of our knowledge is the lowest value amongst the non-fluorinated and non-porous polymers reported in literature. Meanwhile, TmBPPA exhibits excellent overall properties, such as excellent thermostability, good mechanical properties, low moisture absorption, and high bonding strength. As high-performance flexible circuit materials, all these characteristics are highly expected to meet the present and future demands for high density, high speed, and high frequency electronic circuit used in 5G wireless networks.

Abstract Poly(methyl methacrylate) (PMMA)/polystyrene (PS)/carbon black (CB) and poly(ethyl methacrylate) (PEMA)/PS/CB ternary composite films were obtained using solution casting technique to investigate double percolation effect. In both PMMA/PS/CB and PEMA/PS/CB ternary composite films, the CB particles prefer to locate into PS phase based on the results of calculating wetting coefficient, which is also confirmed by SEM images. The conductivity of the films was investigated, and the percolation threshold (ϕc) of both ternary composite films with different polymer blend ratios was determined by fitting the McLachlan GEM equation. Conductivity of PMMA/PS/CB ternary composite films showed a typical double percolation effect. However, due to the double emulsion structure of PEMA/PS polymer blends, the PEMA/PS/CB ternary composite films (PEMA/PS = 50/50) showed a higher ϕc, even CB only located in PS phase, which conflicts with the double percolation effect. A schematic diagram combined with SEM images was proposed to explain this phenomenon.

Abstract Ion segregation is critically important for achieving high ion conductivity for anion exchange membranes (AEMs). Herein, a new bisphenol monomer bearing ten electron-rich phenyl groups was designed and polymerized with various amounts of electron-deficient 4,4′-dihydroxydiphenylsulfone and 4,4′-difluorobenzophenone to yield dense and selective reaction sites for chloromethylation and quaternization. As the most challenging step, chloromethylation was optimized by tuning the reaction temperature, reaction time, and reactant ratios. Ion exchange capacity, water uptake, anion conductivity, mechanical stability, and alkaline stability of the resulting AEMs were characterized in detail. It is found that chloromethylation reaction needed to be carried out at low equivalent of chloromethylation agents to avoid undesirable crosslinking. The QA-PAEKS-20 sample with an IEC of 1.19 mmol·g−1 exhibited a Cl– conductivity of 11.2 mS·cm−1 and a water uptake of 30.2% at 80 °C, which are promising for AEM applications.

Abstract Dynamic control of mesenchymal stem cell (MSC) behaviors on biomaterial surface is critically involved in regulating the cell fate and tissue regeneration. Herein, a stimuli-responsive surface based on host-guest interaction with cell selectivity was developed to regulate migration of MSCs in situ by dynamic display of cell-specific peptides. Azobenzene-grafted MSC-affinitive peptides (EPLQLKM, Azo-E7) were grafted to β-cyclodextran (β-CD)-modified poly(2-hydroxyethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) (PHG) brushes, which were prepared by using surface-initiated atom transfer radical polymerization (SI-ATRP). X-ray photoelectron spectroscopy (XPS), quartz crystal microbalance (QCM), and water contact angle were used to characterize their structure and property. Cell adhesion assay showed that the combination effect of resisting property of PHG and MSC-affinity of E7 could promote the selective adhesion of MSCs over other types of cells such as RAW264.7 macrophages and NIH3T3 fibroblasts to some extent. UV-Vis spectroscopy proved that the competing guest molecules, amantadine hydrochloride (Ama), could release Azo-E7 peptides from the CD surface to different extents, and the effect was enhanced when UV irradiation was employed simultaneously. As a result, the decrease of cell adhesion density and migration rate could be achieved in situ. The cell density and migration rate could be reduced by over 40% by adding 20 μmol/L Ama, suggesting that this type of surface is a new platform for dynamic regulation of stem cell behaviors in situ.

We focus on the distribution and free energy of a wormlike polymer confined between two parallel hard walls. The variation in the distribution and free energy of the wormlike chain as the spacing between the walls decreases (or as the total contour length of the wormlike chain increases or as the persistence length of the chain increases) is simulated. The main reason for these changes is a degradation of the long wormlike chain into a Gaussian long chain under weak confinement.

Poly(lactic acid) (PLA) is one of the most important bio-plastics, and chemical modification of the already-polymerized poly(lactic acid) chains may enable optimization of its material properties and expand its application areas. In this study, we demonstrated that poly(lactic acid) can be readily dissolved in acrylic acid at room temperature, and acrylic acid can be graft-polymerized onto poly(lactic acid) chains in solution with the help of photoinitiator benzophenone under 254 nm ultraviolet (UV) irradiation. Similar photo-grafting polymerization of acrylic acid (PAA) has only been studied before in the surface modification of polymer films. The graft ratio could be controlled by various reaction parameters, including irradiation time, benzophenone content, and monomer/polymer ratios. This photo-grafting reaction resulted in high graft ratio (graft ratio PAA/PLA up to 180%) without formation of homopolymers of acrylic acid. When the PAA/PLA graft ratio was higher than 100%, the resulting PLA-g-PAA polymer was found dispersible in water. The pros and cons of the photo-grafting reaction were also discussed.

In this study, novel electrochromic copolymers of 3,4-ethylenedioxythiophene (EDOT) and (E)-1,2-bis(2-fluoro-4-(4-hexylthiophen-2- yl)phenyl)diazene (M1) with different monomer feed ratios were designed and synthesized electrochemically. Electrochemical and spectroelectrochemical characterizations were performed using voltammetry and UV-Vis-NIR spectrophotometry techniques to test the applicability of copolymers for electrochromic applications. In terms of electrochemical behaviors, addition of an electron-rich EDOT unit into the azobenzenecontaining copolymer increased the electron density on the polymer chain and afforded copolymers with very low oxidation potentials at around 0.30 V. While the homopolymers (P1 and PEDOT) exhibited neutral state absorptions centered at 510 and 583 nm, EDOT-bearing copolymers showed red shifted absorptions compared to those of P1 with narrower optical band gaps. In addition, the poor optical contrast and switching times of azobenzene-bearing homopolymer were significantly improved with EDOT addition into the copolymer chain. As a result of the promising electrochromic and kinetic preperties, CoP1.5-bearing single layer electrochromic device that works between purple and light greenish blue colors was constructed and characterized.

Two octaisobutyl-polyhedral oligomeric silsesquioxanes (oib-POSS) reinforced biodegradable poly(ε-caprolactone) (PCL) composites were prepared via two different methods, i.e., melt compounding and solution casting, which were named as mPCL/oib-POSS and sPCL/oib-POSS, respectively, in this work. Oib-POSS dispersed finely in both composites; moreover, oib-POSS aggregates were larger in mPCL/oib-POSS than in sPCL/oib-POSS. Despite the different preparation methods, oib-POSS obviously promoted the crystallization of PCL, especially in sPCL/oib-POSS, but did not modify the crystal structure of PCL. The storage moduli of PCL were improved significantly in both composites. PCL/oib-POSS composites with enhanced crystallization behavior and improved dynamic mechanical properties were successfully prepared through both methods; moreover, the solution casting method was more effective than the melt compounding method.

Intermolecular synergistic adsorption of indole and carbonyl groups induced by intermolecular hydrogen bonding makes microporous organic polymer (PTICBL) exhibit high CO2 uptake capacity (5.3 mmol·g−1 at 273 K) and selectivities (CO2/CH4 = 53, CO2/N2 = 107 at 273 K). In addition, we find that indole units in the PTICBL networks inhibit the attachment of bacteria (E. coil and S. aureus) on the surface of PTICBL and extend its service life in CO2 capture.

Cross-linked polyamides (cPAs) were prepared through direct bulk Michael addition and subsequent polycondensation. Several mixed hexanediamine multi-esters (HDAMEs) were generated through the Michael addition of 1,6-hexanediamine (HDA) and methyl acrylate (MA) at 50 °C with different HDA/MA molar ratios. Melt polycondensation of HDAMEs then proceeded at 150 or 170 °C in flasks to obtain viscous fluids, and curing was continued in tetrafluoroethylene molds to obtain cPA films. The Michael addition was monitored on the basis of FTIR and ESI-MS spectra. The cPA films were characterized by DSC, TGA, dynamic mechanical analysis, and tensile test. These directly prepared cPAs exhibited Tg of 1–39 °C, tensile strength of up to 45 MPa, and strain at break from 18% to 40%. The cPAs with high tensile strength and good toughness were successfully synthesized through the direct bulk Michael addition from HDA and MA followed with polycondensation.

Poly(L-lactic acid) (PLLA)-based composites exhibit wide applications in many fields. However, most of hydrophilic fillers usually accelerate the hydrolytic degradation of PLLA, which is unfavorable for the prolonging of the service life of the articles. In this work, a small quantity of poly(methyl methacrylate) (PMMA) (2 wt%–10 wt%) was incorporated into the PLLA/carbon nanotubes (CNTs) composites. The effects of PMMA content on the dispersion of CNTs as well as the microstructure and hydrolytic degradation behaviors of the composites were systematically investigated. The results showed that PMMA promoted the dispersion of CNTs in the composites. Amorphous PLLA was obtained in all the composites. Largely enhanced hydrolytic degradation resistance was achieved by incorporating PMMA, especially at relatively high PMMA content. Incorporating 10 wt% PMMA led to a dramatic decrease in the hydrolytic degradation rate from 0.19 %/h of the PLLA/CNT composite sample to 0.059 %/h of the PLLA/PMMA-10/CNT composite sample. The microstructure evolution of the composites was also detected, and the results showed that no crystallization occurred in the PLLA matrix. Further results based on the interfacial tension calculation showed that the enhanced hydrolytic degradation resistance of the PLLA matrix was mainly attributed to the relatively strong interfacial affinity between PMMA and CNTs, which prevented the occurrence of hydrolytic degradation at the interface between PLLA and CNTs. This work provides an alternative method for tailoring the hydrolytic degradation ability of the PLLA-based composites.

Liquid-liquid (L-L) de-mixing and vitrification of solutions of either crystallizable poly(L-lactic acid) (PLLA) or non-crystallizable poly(D/L-lactic acid) (PDLLA) with 50 m% N, N-diethyl-3-methylbenzamide (DEET) were analyzed by calorimetry and cloud-point measurements, which allows drawing conclusions about the effect of polymer stereochemistry on the phase behavior. Regardless of the PLA stereochemistry, vitrification of the solutions on fast cooling, hindering crystallization of PLLA, occurred below −20 °C and suppressed prior L-L de-mixing. The experimental results prove that crystallization in samples containing crystallizable PLLA, observed at around 55 °C on slow cooling, is not preceded by L-L de-mixing.

Abstract Four truxene-based conjugated microporous polymers (Tr-CMPs) were prepared via different synthetic methods and their structure-property relationships were studied. The polymer networks have high Brunauer-Emmett-Teller (BET) specific surface areas ranging from 554 m2·g−1 to 1024 m2·g−1. Pore sizes of the CMPs with different linkers are mainly located between 0.60 and 1.96 nm. Among all the Tr-CMPs, Tr-CMP4 has the highest BET surface area of 1024 m2·g−1 and exhibits the highest H2 uptake of 0.88 wt%. Tr-CMP2 prepared by Suzuki-Miyaura coupling reaction has the highest photoluminescence quantum yields (PLQYs) of 13.06% and CO2 uptake of 6.25 wt%.

In this study, two new dendronized nonlinear optical (NLO) polymers were synthesized with high FTC chromophore loading density by introduction of high generation chromophore dendrons on the side chains. Due to their suitable molecular weights, both of them possessed good solubility in common solvents. They also inherited the advantages of dendrimers (large NLO coefficient), especially for PG2 whose NLO coefficient d33 value was as high as 282 pm·V-1. Also, PG2 had a good temporal stability with 80% of its maximum value being retained at the temperature as high as 129 °C.

For the solid-solid transformation from form II to form I of isotactic polybutene-1 (iPB), the temperature dependence of form I nucleation and growth was deemed to control the transformation process. However, the relationship between form I formation and form II disappearance in the transformation process is not clear. In this work, the spontaneous crystal transformation from form II to I of iPB with 81 mol% mmmm sequence concentration is studied firstly by tracking the two processes, the decay of form II and the yielding of form I in a wide range of temperature spanning from 0 °C to 50 °C and in a long transformation time ranging from 5 min to 65 days with in situ FTIR and WAXD. Unlike the literature reports, the decay rate of form II is firstly found to be lower than the yielding rate of form I at all studied temperatures, especially at low transition temperature. This is attributed to the amorphous chains which locate near crystal lamella participating into the nucleation of form II. The regular chain folding and growth of iPB form I from amorphous chains containing short isotactic sequences also lead to an increase in crystallinity of form I compared with that of initial form II crystallized at 60 °C. An increase in the annealing temperature results in decrease in crystallinity and increase in lamellae thickness of iPB form I.

Abstract PEDOT, or poly(3,4-ethylenedioxythiophene), is among the most successful conducting polymer products because of its stable conductivity, colloidal processability, and rich assembly behavior. Since the very first patents on PEDOT filed in 1988, the material has been widely explored for decades in many applications. In this review, a comprehensive summary on the synthesis, processing and post-treatment of PEDOT will be presented for the sake of the discussion on PEDOT and its nanocomposites for energy storage. Knowing what PEDOT lends itself to the electrode materials is of importance to the rational design of energy storage devices that maximize the real-world performance. Based on these discussions, a roadmap for the development of PEDOT as promising multifunctional electrode component is presented.

In principle, conjugated polymers can work as electron donors and thus as low-cost p-type organic semiconductors to transport holes in photovoltaic devices. With the booming interests in high-efficiency and low-cost solar cells to tackle global climate change and energy shortage, hole transporting materials (HTMs) based on conjugated polymers have received increasing attention in the past decade. In this perspective, recent advances in HTMs for a range of photovoltaic devices including dye-sensitized solar cells (DSSCs), perovskite solar cells (PSCs), and silicon (Si)/organic heterojunction solar cells (HSCs) are summarized and perspectives on their future development are also presented.

Electromagnetic interference (EMI) shielding materials are in great demand in electronic equipment and our surrounding environment to resist the increasing serious radiation pollution. Compared with their metal counterparts, conductive polymer composites (CPCs) have unique advantages of lightweight, corrosive resistance, low cost, and excellent processability, and are therefore an ideal choice for developing high-performance EMI shielding materials. However, CPCs based EMI shielding materials are limited to high filler loading, which caused poor mechanical properties and processability. Here, we demonstrate a facile and highly scalable approach to develop high-performance EMI shielding materials with low filler loading by using miscible poly(phenylene oxide)/polystyrene (PPO/PS) blend as the matrix. In contrast to PS/carbon nanotubes (CNTs) composites, PPO/PS/CNTs composites show much higher EMI shielding effectiveness caused by good dispersion of CNTs and highly interconnected conductive network. An excellent EMI shieling effectiveness of 23–25 dB is achieved for PPO/PS/10%CNTs composites with a thickness of only 375 µm, which is superior to most of reported polymer/CNTs composites prepared by melt-compounding. In addition, the results show that although absorption is the major shielding mechanism, the contribution of reflection is also important and closely related to the connectivity of conductive network, as well as the electrical conductivity of the CPCs.

A bulk Poly(vinyl alcohol)/ZIF-8 (PVA/ZIF-8) porous composite with aligned porous structure was prepared by ice-templating method. The microstructure of PVA/ZIF-8 porous composites was characterized by scanning electron microscopy (SEM). The results showed that the composites had regular pore structure and ZIF-8 nanoparticles were evenly distributed on the skeleton of PVA. X-ray diffraction (XRD) test results showed that the crystalline structure of ZIF-8 was well preserved in the composites. The specific surface area of the composite was characterized by nitrogen adsorption/desorption test. The specific surface area of the composite was up to 1160 m2·gt1. PVA/ZIF-8 porous composites could also support a certain weight with almost no volume shrinkage. The carbon dioxide adsorption quantity of the composite was up to 11.3 cm3·gt1, proving that PVA/ZIF-8 porous composite has a good application prospect in the field of carbon dioxide adsorption.

A series of novel poly(amide-imide) (PAI) films with different amide contents were prepared from pyromellitic dianhydride and four amide-containing diamines. These PAI films exhibited excellent mechanical and thermal properties with tensile strength of 203.7–297.4 MPa and Tg above 407 °C. The rigid backbone structures combined with strong intermolecular interactions provided PAI films with ultralow in-plane CTE values from −4.17 ppm/°C to −0.39 ppm/°C in the temperature range of 30–300 °C. The correlation between thermal expansion behavior and aggregation structures of PAI film was investigated. The results suggested that hydrogen bonding interactions could be maintained even at high temperature, thus resulting in good dimension reversibility of films in multiple heating-cooling cycles. It is demonstrated that dimensional stabilities of PAI films are determined by the rigidity, orientation, and packing of molecular chains. Heat-resistant PAI films with ultralow CTE can be developed as flexible substrates by regulating backbones and aggregation structures for optoelectronic application.

Proton conductivity of proton exchange membranes (PEMs) strongly relies on microscopic morphology, which can be modulated by engineering the distribution of ionic groups. Herein, poly(arylene ether)s with densely distributed allyl functionalities are polymerized from a tetra-allyl bisphenol A monomer. The subsequent thiol-ene addition with sodium 3-mercapto-1-propanesulfonate yields comb-shaped sulfonated fluorinated poly(arylene ether)s (SFPAEs) with ion exchange capacities (IECs) ranging from 1.29 mmol·g−1 to 1.78 mmol·g−1. These SFPAEs exhibit superior proton conductivity over the whole temperature range, which is attributed to the enhanced hydrophilic/hydrophobic phase separation as evidenced by small angle X-ray scattering characterizations. The SFPAE-4-40 with an IEC of 1.78 mmol·g−1 shows the largest proton conductivity of 93 mS·cm−1 at room temperature under fully hydrated condition, higher than that of Nafion 212. Furthermore, the vanadium redox flow battery (VRFB) assembled with SFPAE-4-40 separator exhibits higher energy efficiency than the VRFB assembled with Nafion 212.

A general model was developed to predict the temperature-dependent modulus and yield strength of different thermoplastic polymers. This model, which depends on only two parameters with clear and specific physical meanings, can describe the temperature-dependent modulus and yield strength of thermoplastic polymers over the full glass transition region. The temperature-dependent modulus and yield strength of three thermoplastic polymers were measured by uniaxial tension tests over a temperature range of 243–383 K. The predictions showed excellent agreement with the experimental data. Sensitivity analysis of model input parameters showed negligible effect on the present general model. The universality of the present general model was further validated, showing excellent agreement with published experimental data on other thermoplastic polymers and their composites.

In this work, step-cycle tensile behavior of two bimodal polyethylene (PE) materials, a PE100 grade pipe material, XS10, and a PE100-RC (Resistant Crack) grade pipe material, XSC50, was comparatively investigated. By decomposing the strain into a recoverable part and an unrecoverable part, it was found that the deformation recovery capability of XSC50 during stretching was larger than that of XS10. Structural evolution characterized by in situ synchrotron small angle X-ray scattering indicated that the fragmentation of initial crystals in XSC50 occurred at lower strain than in XS10. Considering that XSC50 had relatively small lamellar thickness and similar crystallinity to XS10, we speculated that the larger deformation recovery capability of XSC50 during stretching probably derived from stronger entangled amorphous region caused by larger density of tie molecules and entanglements, which were usually regarded to have a significant influence on the slow crack growth (SCG) resistance of PE materials. As expected, the experimental result of strain hardening modulus test suggested that the deformation recovery capability during stretching was positively correlated with the SCG resistance for XS10 and XSC50 used in this work. The step-cycle tensile test had the potential to be developed into a supplement for comparison of SCG resistance of PE materials.

As a typical plant virus which has biocompatibility and high transfection efficiency, tobacco mosaic virus (TMV) has shown broad application potential in drug or gene delivery field. Elucidating its intracellular trafficking is of great importance in investigation of its cytotoxicity, targeting site, and delivery efficiency, and is advantageous to designing new TMV-based drug delivery systems with different targets. By taking advantage of the regulated pH value of different organelles in a mammalian cell, we exploit a pH detection strategy to investigate the intracellular trafficking pathway of TMV. Here, we report a single-wavelength excited ratiometric fluorescent pH probe. This probe is constructed by simultaneously coupling pH-sensitive fluorescein isothiocyanate (FITC) and pH-insensitive rhodamine B isothiocyanate (RBIRC) onto the inner surface of TMV. The fluorescence intensity ratio of FITC to RBITC excited at 488 nm responds specifically towards pH value over other interferential agents. By taking use of this single-wavelength excited ratiometric pH probe and confocal laser scanning microscopy, it is shown that the endocytosed TMV is located in a pH decreasing microenvironment and eventually enters lysosomes. This work may provide important guidance on construction of TMV-based nano carriers.

The role of mold temperature on the morphology and properties of rotational shearing polyethylene (PE) pipes was studied via a self-developed rotational shear system (RSS). The result indicated that when the mold temperature was 150 °C, the hoop tensile strength and Vicat softening temperature were enhanced rapidly, which were 383.6% and 137.9% higher than those of the conventional PE pipes, respectively. Morphology and crystal structure studies by SEM and DSC revealed that once the rotational shear was applied, the shish-kebab structure began to appear. With the increase of the mold temperature, due to the relaxation of most of the oriented molecular chains, the preservation of shish-kebab structure became difficult. When the mold temperature was 190 °C, only the inner layer of the pipes, where the cooling rate was the largest, could preserve the shish-kebab structure. According to WAXD, there was less shish structure, and the growth of kebab was distorted in the inner layer of the pipes at 210 °C. The result of SAXS suggested that the length of shish changed most within the temperature range from 170 °C to 190 °C. The results of DSC and WAXD showed less change in crystallinity and degree of orientation between the two temperatures. It can be concluded that the reduction of shish length leads to a decrease in mechanical properties and heat-resistance.

Polylactide (PLA), methyl methacrylate-butadiene-styrene copolymer (MBS), and poly(propylene carbonate) polyurethane (PPCU) were blended and subjected to blown film process. The rheological, mechanical, morphological, thermal, and crystalline properties of the PLA/MBS/PPCU ternary blends and the mechanical properties of the resulting films were studied. Results of mechanical test showed that PPCU and MBS could synergistically toughen PLA. The impact strength of 50/10/40 PLA/MBS/PPCU blend (74.7 kJ/m2) was about 7.5 times higher than that of the neat PLA (10.8 kJ/m2), and the elongation at break of 50/10/40 PLA/MBS/PPCU blend (276.5%) was higher by about 45 times that of PLA (6.2%). The tear strength of PLA/MBS/PPCU films was 20 kN/m higher than that of PLA, and the elongation at break (MD/TD) of 50/10/40 PLA/MBS/PPCU films was 271.1%/222.3%, whereas that of PLA was only 2.7%/3.0%. POM observations displayed that the density of spherulite nucleation increased and the size of crystalline particles decreased with the addition of MBS. With increasing PPCU content from 5% to 20%, the density of spherulite nucleation increased and the size of crystalline particles decreased continuously, but the nucleation density of spherulites was slightly lowered with increasing PPCU content from 30% to 40%. The PLA/MBS/PPCU films exhibited excellent mechanical properties, which expanded the application range of these biodegradable films.

This article presents a brief overview of recent advances in azo-containing supramolecular systems. In literature, it has been shown that azo supramolecular polymers and their composite materials exhibit fast and intelligent responses to various external stimuli, such as temperature, pH change, redox reagents, ligands, coupling reagents, etc. In applications, these systems are widely used for molecular motors, shape memory, liquid crystal, solar thermal energy storage, signal transmission, intelligent encryption, and other purposes. Furthermore, these systems can function as key components for device upgrade processing. However, the design and rules of azo supramolecular polymers are still not supported by an exact theory. Information about the relationship between the spatial structure and behavior is lacking, and new supramolecular materials cannot be designed by adding functional moieties to known azo polymers. Based on the current research status, this review mainly summarizes the structural design principles as well as structures and applications of known azo supramolecules; meanwhile, it highlights the emerging development fields, recent advances, and prospects in fabricating self-assembling intelligent supramolecular systems with azo supramolecular polymers as responsive units. The goal of this review is to bring new inspiration to researchers who want to optimize the chemical structure, steric conformation, electrostatic environment, and specific molecular functionalization.

In this work, poly(vinylidene fluoride) (PVDF) membranes with hydrophilicity as well as preeminent mechanical strength and dye removal efficiency were fabricated by blending with three dimensional hydroxyapatite nanoparticles (HAPNPs). Surface chemical composition and morphology of the prepared membranes were systematically investigated by ATR-FTIR, XPS, XRD, FESEM, and EDS mapping analyses. The results verified that a large number of HAPNPs were successfully embedded on the modified membrane cross-sections. Moreover, HAPNPs content in the casting solution is an important factor that could have profound influence on the structures and performances of PVDF/HAPNPs blend membranes. The optimal membrane M2 with 2 wt% HAPNPs exhibited excellent hydrophilicity, outstanding mechanical strength of 19.60 MPa, and high water flux of (2466 ± 31) Lm−2h−1. The maximum static adsorption capacity of the optimal membrane was about 10.83 mg/g, which is 3.75 times that of the pristine PVDF membrane (2.89 mg/g). PVDF/HAPNPs membranes were not only utilized for static adsorption, but also applied to dynamic dye removal. The possible adsorption mechanism between Congo red (CR) and HAPNPs embedded on the blend membranes was firstly discussed in this work. HAPNPs interacted with CR via Lewis reaction, hydrogen bond interaction, as well as electrostatic attraction to achieve the adsorption effect. Herein, the PVDF/HAPNPs blend membranes with extraordinary hydrophilicity, mechanical strength, and dye removal efficiency possess tremendous potential for practical applications of wastewater treatment.

Interlocked-ring polymers, also known as polycatenanes, possess an interesting molecular architecture. These polymers are composed of many interlocked rings in a linear chain. The topological constrain between neighboring rings distinguishes the interlocked-ring polymer from its linear counterpart. Here we present extensive molecular dynamic simulations on the interlocked-ring polymers and analyze the static properties of the polymer. By applying external forces to the polymer, we also study the force-extension curves of the polymer, which provides rich information about the mechanical properties of the interlockedring polymers.

The manufacturing process of poly(vinylidene fluoride) microporous films containing through flow channels and permeable to liquids has been elaborated. The process is based on polymer melt extrusion with subsequent stages of annealing, uniaxial extensions (“cold” and “hot” drawing), and thermal stabilization. The effect of orientation parameters (melt draw ratio and extension degrees) on overall porosity, permeability, morphology, and content of polar piezoactive β-phase in crystalline structure of the films was investigated by filtration porosimetry, sorptometry, scanning electron microscopy, X-ray scattering, and mechanical properties measurements. It is shown that the through pores were formed by a percolation mechanism. It is observed that permeability and the β-phase content increased with the growth of extension degree at the pore formation stages but the portion of β-crystallites decreased with increasing melt draw ratio at extrusion, which permitted to regulate the combination of through permeability and piezoactivity values by variation of the preparation process parameters.

In this study, a novel waterborne polyurethane (WPU) with azobenzene-containing (azo-containing) pendant groups was synthesized by isophorone diisocyanate, long-chain diol of polycaprolactone, 2-ethyl-2-methyl-butanoic acid (2,2-dimethylolpropionic acid), 10-(4-(phenyldiazenyl)phenoxy)decyl-3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate, and N,N-diethyl-ethanamine (triethylamine). Moreover, the influence of ultraviolet and visible (UV-Vis) light irradiation on the viscoelasticity of azo-containing WPU film in terms of the reversible trans-cis photoisomerization of azo-containing pendant groups was investigated by UV-Vis light spectroscopy, atomic force microscopy, and dynamic thermomechanical analysis. The results revealed that the adhesion of azo-containing WPU with single crystal silicon atomic force microscope probe was about 13 nN when irradiated by 450 nm Vis light for 60 s at 25 °C. Subsequently, the adhesion increased to 82 nN after irradiation with 365 nm UV light for 60 s at 25 °C. In addition, the azo-containing WPU presented a photo-induced reversible transition of tensile modulus and tanδ in the range from about 2 MPa to 22 MPa and 6000 to 0.35 with UV-Vis light cyclic irradiation for 120 s at 25 °C, respectively.

Drug-resistance and drastic side effects are two major issues of traditional chemotherapy which may result in trail failure even death. Nanoparticle-mediated multidrug combination treatment has been proven to be a feasible strategy to overcome these challenges. In the present study, amphipathic block polymer of methoxyl poly(ethylene glycol)-poly(aspartyl(dibutylethylenediamine)-co-phenylalanine) (mPEG-P(Asp(DBA)-co-Phe)) was synthesized and self-assembled into pH-responsive polymeric vesicle. The vesicle was utilized to co-deliver cancer-associated epidermal growth factor (EGFR) inhibitor of afatinib and DNA-damaging chemotherapeutic doxorubicin hydrochloride (DOX) for enhanced non-small-cell lung cancer (NSCLC) therapy. As evaluated in vitro, the pH-responsive design of nanovesicle resulted in a rapid release of encapsulated drugs into tumor cells and caused enhanced cell apoptosis. In addition, in vivo therapeutic studies were conducted and the results evidenced that the co-delevery of DOX and afatinib using pH-sensitive nanovector was a promising strategy for NSCLC treatment.

The scaling relations among the mean end-to-end distance of polymer along the channel < R∥ >, the polymer length N, and the effective diameter of channel De were investigated for flexible and semi-flexible polymer chains confined in long cylindrical channels. For the flexible polymer chain, scaling relation < R∥ > ∼ NDe-0.7 was found in the classic de Gennes regime at lp2/b < De < Rg with lp the persistence length, b the bond length, and Rg the radius of gyration of polymer. For the semi-flexible polymer, ∼ NDe-1 in the transition regime lp < De < xlp (x > 1) and ∼ De-0.7 in the classic de Gennes regime at larger De > xlp were observed. The simulation results revealed that the scaling relation in the transition regime was due to the rod-like behavior of the semi-flexible polymer in the small regime lp < De < xlp.

A well-defined quadruple hydrogen bonding strategy involving dimerization of 2-ureido-4[1H]-pyrimidone (UPy) units is innovatively designed to prepare polyureas with high overall mechanical properties. Three polyureas containing different amounts of UPy units were synthesized by replacing a portion of isophorone diisocyanate (IPDI) with a UPy-derived diisocyanate. The formation of quadruple hydrogen bonds in hard segments via UPy dimers was confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the polyureas were evaluated by uniaxial tensile testing. Compared to the polyurea without UPy units, remarkable improvements in Young’s modulus, tensile strength, and toughness were simultaneously achieved when UPy units were incorporated. The mechanism behind the strong strengthening effect rooted in the stronger intermolecular forces among hard segments brought by the quadruple hydrogen bonds, which were stronger than the inherent bidentate and monodentate hydrogen bonds among urea groups, and the slower soft segmental dynamics reaveled by both increased Tg and relaxation time of the soft segments. The mechanism behind the strong toughening effect was ascribed to more effective energy dissipation brought by the quadruple hydrogen bonds that served as stronger sacrificial bonds upon deformation. This work may offer new insight into the design of polyurea elastomers with comprehensively improved mechanical properties.

Computational strategies have been employed to investigate the influence of the nature of monomers and cross-linker in order to design three dimensional imprinted polymers with selective recognition sites for L-phenylalanine benzyl ester (L-PABE) molecule. Here, computational chemistry methods were applied to screen the molar quantity of functional monomers that interact with one mole of the template molecule. Effects of the nature of functional monomer, cross-linker, and molar ratio were determined computationally using density functional calculations with B3LYP functional and generic 6–31G basis set. Methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) were used as the functional monomer and crosslinking agent, respectively. L-PABE imprinted polymer layered on multiwalled carbon nanotube (MWCNT) and conventional bulk MIP were synthesised and characterized as well. To investigate the influence of pre-organization of binding sites on the selectivity of L-PABE, respective non-imprinted polymers were also synthesised. MWCNT-MIPs and MIPs exhibited the highest adsorption capacity towards L-PABE. The synthesized polymers revealed characteristic adsorption features and selectivity towards L-PABE in comparison with those of its enantiomer analogues.

This contribution reports an efficient approach for preparing polycarbonate block terpolymers by immortal stepwise copolymerization of CO2 with different epoxides in the presence of enol chain transfer, mediated by robust cobalt catalyst systems consisting of the fluorine substituted salenCo(III)NO3 or biphenol-linker bimetallic Co(III) complex in conjunction with an ionic cocatalyst, PPNX (PPN = bis(triphenylphosphine)iminium, X = NO3− or 2,4-dinitrophenoxide). Various polycarbonate block terpolymers were obtained in perfectly unimodal distribution of their molecular weights with narrow polydispersity. They all possessed only one broad glass transition temperature, which could be adjusted by altering the length of different polycarbonate segments.

Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization (ROP) of lactones, including δ-valerolactone, ε-caprolactone, and δ-hexalactone. The catalysts are prepared by simply mixing tetra-n-butyl ammonium hydroxide and a (thio)urea at elevated temperature under vacuum, and used in cooperation with an alcoholic initiator. The performance of the catalyst is readily adjusted and optimized through variation of the (thio)urea precursor, catalyst composition, and reaction condition. Urea-derived catalysts are generally superior to thiourea-derived ones. Provided with proper N-substituents, the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification, even at high monomer conversion and/or substantially extended reaction time. In addition to acidity, structural symmetry of the urea also proves decisive for the catalytic activity, which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.

A series of nickel complexes {4a: [(2,6-iPr2C6H3)N=CHC16H12O]Ni(Me)(Py), 4b: [(2,6-iPr2C6H2OCH3)N=CHC16H12O]-Ni(Me)(Py), 4c: [(2,6-iPr2C6H2Cl)N=CHC16H12O]Ni(Me)(Py), and 4d: [(2,6-iPr2C6H2CF3)N=CHC16H12O]Ni(Me)(Py)} based on β-ketiminato ligands bearing various electron-donating or electron-withdrawing substituents on the para-position of the aniline group were synthesized and unambiguously characterized. The X-ray crystallographic analysis showed that complexes 4b and 4d adopted a near-square-planar geometry, and the anilines bearing a para-OMe or −CF3 group were found to situate on the axial position of the metal center. All complexes exhibited high activities up to 1.25 × 107–1.35 × 107 gPNB·molNi−1·h−1 toward norbornene (NBE) addition polymerization (conversion > 91.2% in 2 min) under low loading of B(C6F5)3 (B/Ni = 3) at 30 °C, affording polymers with high molecular weight up to 2.54 × 106–3.18 × 106. Different levels of decrease in catalytic activities could be observed for all catalysts as the reaction temperature increased; 4d bearing a strong electron-withdrawing −CF3 group showed the highest activity at 70 °C, while others exhibited notable decrease in catalytic activity with the raise in reaction temperature. Complexes 4a–4d showed remarkable tolerance to polar groups and could efficiently promote the copolymerization of NBE with its polar derivatives, including NBE bearing small acetate and hydroxyl group, as well as bulky oligomers, yielding copolymers with high functional NBE incorporations. Novel NBE copolymers with high functional comonomer incorporations and improved solubility were obtained in high yields.

Owing to the excellent filtration performance and low energy cost, polymeric nanofibers microfiltration (MF) membranes have attracted increasing attentions. Poly(arylene sulfide sulfone) (PASS), as one of the structurally modified polymers based on poly-(phenylene sulfide) (PPS), has been selected as the raw material to fabricate nanofibers MF membranes via electrospun techniques. The effects of PASS solution and the electrospinning processing parameters on the structural morphology of nanofibers were investigated in detail. The average diameter of PASS nanofibers was (296 ± 46) nm under the optimal condition: polymer concentration of 0.27 g·mL−1 PASS/DMI, applied voltage of 20 kV, and speed of collector drum of 300 r·min−1. And then the multi-layer PASS nanofibers MF membranes were fabricated from cold-pressing the optimized PASS nanofibers (as-prepared PASS nanofibers) membrane. The morphology, porosity, pore size, mechanical properties, and surface wettability of the multi-layer PASS nanofibers MF membranes could be tuned by the layers of as-prepared nanofibers membrane. The results demonstrated that the membrane with 6 layers (marked as PASS-6) exhibited the smallest porosity, smallest pore size, highest mechanical property, and best surface wettability. Meanwhile, the multi-layer PASS nanofibers MF membranes showed that the rejection ratio gradually increased, while the pure water flux decreased with increasing membranes thickness. The PASS-6 membrane exhibited large water flux of 747.76 L·m−2·h−1 and high separation efficiency of 99.9% to 0.2 µm particles, making it a promising candidate for microfilter.

In this study, we investigate the motion of polymer segments in polymer/nanoparticle composites by varying nanoparticle (NP) volume fractions. By studying the probability distribution of segment displacement, segment trajectory, and the square displacement of segment, we find the intermittent motion of segments, accompanied with the coexistence of slow and fast segments in polymer nanocomposites (PNCs). The displacement distribution of segments exhibits an exponential tail, rather than a Gaussian form. The intermittent dynamics of chain segments is comprised of a long-range jump motion and a short-range localized motion, which is mediated by the weakly attractive interaction between NP and chain segment and the strong confinement induced by NPs. Meanwhile, the intermittent motion of chain segments can be described by the adsorption-desorption transition at low particle loading and confinement effect at high particle loading. These findings may provide important information for understanding the anomalous motion of polymer chains in the presence of NPs.

A series of new bisphosphine-monoxide (BPMO) ligands based on benzothiophene backbone and the corresponding palladium complexes {K2-2-P(O)(Ph)2-3-PR1R2-C8H4S}PdMeCl {2a: R1 = R2 = Ph; 2b: R1 = R2 = 2-OMe-Ph; 2c: R1 = R2 = 2-CF3-Ph; 2d: R1 = Ph, R2 = 2-(2′,6′-(OMe)2C6H3)-C6H4} were synthesized and fully characterized by 1 H-, 13C-, 31P-, and 2D-NMR spectroscopy and single-crystal X-ray diffraction. In the presence of Na+B[3,5-(CF3)2C6H3]4− (NaBArF), these complexes showed very high activities (up to 2.0 × 107 gmo−1·h−1) for ethylene polymerization. More significantly, these catalysts enabled the copolymerization of ethylene with a broad scope of commercially available polar comonomers such as acrylates, acrylic acid, acrylonitrile, vinyltrialkoxysilane, allyl acetate, and long-chain 6-chloro-1-hexene to give functionalized polyethylene with reasonable catalytic activities (up to 106 g·mol−1·h−1) and incorporations (up to 5.3 mol%). This contribution suggests that, besides the modulation of conventionally steric and electronic factors, the connectivity (at different linking positions) of BPMO (P,O) donors to the heteroaryl backbone also greatly influences the catalyst properties in terms of catalytic activity, polymer branching content, comonomer scope, and comonomer incorporation.