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Weakly Ionically Bound Thermosensitive Hyperbranched Polymers
Langmuir ( IF 3.7 ) Pub Date : 2021-02-23 , DOI: 10.1021/acs.langmuir.0c03487
Hansol Lee 1 , Alexandr Stryutsky 2 , Akhlak-Ul Mahmood 3 , Abhishek Singh 3 , Valery V. Shevchenko 2 , Yaroslava G. Yingling 3 , Vladimir V. Tsukruk 1
Affiliation  

We synthesized novel amphiphilic hyperbranched polymers (HBPs) with variable contents of weakly ionically tethered thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) macrocations in contrast to traditional covalent linking. Their assembling behavior was studied below and above the lower critical solution temperature (LCST). The HBPs underwent a morphological transition under changing temperature and ionic strength due to the LCST transition of PNIPAM and the reduction in the ionization degree of terminal ionic groups, respectively. We suggest that, in contrast to traditional branched polymers, ionically linked PNIPAM macrocations can reversibly disassociate from the sulfonate groups and form mobile coronas, endowing the dynamic micellar morphologies. In addition, assembly at the air–water interface confined PNIPAM macrocations and resulted in the formation of heterogeneous Langmuir–Blodgett (LB) monolayers with diverse surface morphologies for different peripheral compositions with circular domains formed in the condensed state. The HBPs with 25% PNIPAM showed larger and more stable circular domains that were partially preserved at high compression than those of HBPs with 50% PNIPAM. Moreover, the LB monolayers showed variable surface mechanical and surface charge distribution, which can be attributed to net dipole redistribution caused by the behavior of mobile PNIPAM macrocations and core sulfonate groups.

中文翻译:

弱离子束缚的热敏性超支化聚合物

我们合成了具有可变含量的弱离子束缚热响应性聚(N)的新型两亲性超支化聚合物(HBP)-异丙基丙烯酰胺)(PNIPAM)大阳离子与传统的共价连接相反。在较低的临界溶液温度(LCST)之下和之上,研究了它们的组装行为。由于PNIPAM的LCST转变和末端离子基团的电离度降低,HBP在温度和离子强度变化的条件下分别发生了形态转变。我们建议,与传统的支化聚合物相反,离子连接的PNIPAM宏观阳离子可以可逆地与磺酸盐基团解离并形成可移动的电晕,赋予动态胶束形态。此外,在空气-水界面处的组装限制了PNIPAM宏观阳离子,并导致形成了具有不同表面形态的异质Langmuir-Blodgett(LB)单层,这些表面形态具有在凝结状态下形成的圆形结构域的不同外围成分。PNIPAM含量为25%的HBPs与PNIPAM含量为50%的HBPs相比,显示出更大,更稳定的环状结构域,在高压缩下部分保留。此外,LB单分子层显示出可变的表面机械和表面电荷分布,这可归因于由移动PNIPAM宏观阳离子和核心磺酸盐基团的行为引起的净偶极子再分布。PNIPAM含量为25%的HBPs与PNIPAM含量为50%的HBPs相比,显示出更大,更稳定的环状结构域,在高压缩状态下部分保留。此外,LB单分子膜显示出可变的表面机械和表面电荷分布,这可以归因于由移动PNIPAM宏观阳离子和核心磺酸盐基团的行为引起的净偶极子再分布。PNIPAM含量为25%的HBPs与PNIPAM含量为50%的HBPs相比,显示出更大,更稳定的环状结构域,在高压缩状态下部分保留。此外,LB单分子层显示出可变的表面机械和表面电荷分布,这可归因于由移动PNIPAM宏观阳离子和核心磺酸盐基团的行为引起的净偶极子再分布。
更新日期:2021-03-09
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