Steric hindrance effect on thermo‐responsive behaviors of well‐defined water‐soluble semi‐rigid polymers
Steric hindrance effect on thermo‐responsive behaviors of well‐defined water‐soluble semi‐rigid polymers
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DOI：
10.1002/pola.26740
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发表时间：
2013-08
期刊：
影响因子：
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通讯作者：
Peng Liu;Qian Tan;Liangbo Xiang;Hailiang Zhang
中科院分区：
文献类型：
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作者：
Peng Liu;Qian Tan;Liangbo Xiang;Hailiang Zhang
三个系列的水溶性半刚性温敏聚合物具有明确的分子量基于介晶夹套液晶聚合物，聚[双（N-（2-羟丙基）吡咯烷酮）2-乙烯基对苯二甲酸酯] [P（2-HPPVTA）]，聚[双（N-（1-甲基-2-羟乙基）吡咯烷酮）2-乙烯基对苯二甲酸酯] [P（1-M-2-HEPVTA）]和聚[双通过可逆加成-断裂链转移聚合合成了[（N-羟丙基吡咯烷酮）2-对苯二甲酸乙烯酯]（PHPPVTA）。研究了空间位阻效应对半刚性水溶性聚合物（P（2-HPPVTA）、P（1-M-2-HEPVTA）和PHPPVTA）液晶性和温度响应行为的影响。从分子结构上看，P（1-M-2-HEPVTA）的空间位阻比P（2-HPPVTA）的空间位阻大。偏光显微镜和一维广角X射线衍射结果表明，P（2-HPPVTA）和P（1-M-2-HEPVTA）均为柱状晶相，表明空间位阻效应不影响聚合物的液晶行为。动态光散射结果表明，在相同质量浓度和相同分子量的情况下，P（1-M-2-HEPVTA）比P（2-HPPVTA）具有更低的浊点。在P（2-HPPVTA）溶液中比在P（1-M-2-HEPVTA）溶液中观察到更显著的分子量和浓度对浊点的依赖性。我们还发现，P（2-HPPVTA）和P（1-M-2-HEPVTA）溶液在D2 O中的浊点低于在H2O中的浊点。值得注意的是，PM-2的浊点在D2 O中比在H2O中低9.9 °C，远不如PH-2的浊点差明显。P（2-HPPVTA）和P（1-M-2-HEPVTA）的热响应行为的差异是由于其侧基存在空间位阻效应所致。© 2013威利期刊公司. J.波利姆科学，A部分：聚合物Chem.2013，51，3429-3438
Three series of water‐soluble semi‐rigid thermo‐responsive polymers with well‐defined molecular weights based on mesogen‐jacketed liquid crystal polymers, poly[bis(N‐(2‐hydroxypropyl) pyrrolidone) 2‐vinylterephthalate] [P(2‐HPPVTA)], poly[bis(N‐(1‐methyl‐2‐hydroxyethyl) pyrrolidone) 2‐vinylterephthalate] [P(1‐M‐2‐HEPVTA)] and poly[bis(N‐hydroxypropyl pyrrolidone) 2‐vinylterephthalate] (PHPPVTA) have been synthesized via reversible addition‐fragmentation chain transfer polymerization. The steric hindrance effects on liquid crystalline property and thermo‐responsive behaviors of semi‐rigid water‐soluble polymers (P(2‐HPPVTA), P(1‐M‐2‐HEPVTA), and PHPPVTA) were carefully investigated. From molecular structure, the steric hindrance of P(1‐M‐2‐HEPVTA) is stronger than that of P(2‐HPPVTA). Polarized light microscope and one‐dimensional wide‐angle X‐ray diffraction revealed that both the P(2‐HPPVTA) and P(1‐M‐2‐HEPVTA) display a columnar nematic phase, indicating that the steric hindrance effect do not affect liquid crystalline behavior of the polymers. The dynamic light scattering results demonstrated that P(1‐M‐2‐HEPVTA) exhibited lower cloud point compared with that of P(2‐HPPVTA) at the same mass concentration and the same molecular weight. The more significant molecular weight and concentration dependence on cloud point have been observed in P(2‐HPPVTA) solution than in P(1‐M‐2‐HEPVTA) solution. We also discovered that the cloud points of both P(2‐HPPVTA) and P(1‐M‐2‐HEPVTA) solution are lower in D2O than in H2O. It is noted that the cloud point of PM‐2 is 9.9 °C lower in D2O than in H2O, much less pronounced than the cloud point difference of PH‐2. The differences of thermo‐responsive behaviors between P(2‐HPPVTA) and P(1‐M‐2‐HEPVTA) were resulted from the steric hindrance effect existed in their side groups. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2013,51, 3429–3438