Combinations of microphase separation and terminal multiple hydrogen bonding in novel macromolecules.
Combinations of microphase separation and terminal multiple hydrogen bonding in novel macromolecules.
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DOI：
10.1021/ja020123e
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发表时间：
2002-07
影响因子：
15
通讯作者：
K. Yamauchi;Jeremy R. Lizotte;D. Hercules;M. Vergne;T. Long
中科院分区：
文献类型：
--
作者：
K. Yamauchi;Jeremy R. Lizotte;D. Hercules;M. Vergne;T. Long
介绍了端部多氢键聚合物（MHB）的合成和表征，如聚苯乙烯（PS）、聚异戊二烯（PI）和微相分离的PS-b-PI嵌段共聚物，它们具有可控的分子量和窄的分子分布。羟基封端的聚合物前体的制备使用活性阴离子聚合和随后的定量终止与环氧乙烷。MHB聚合物是以受控的方式合成的，通过这些定义明确的大分子醇与过量的异佛尔酮二异氰酸酯的端基改性和随后的异氰酸酯封端的聚合物中间体与甲基异胞嘧啶的衍生化。的终端MHB聚合物的玻璃化转变温度是可再现地高于两个非官能化和羟基封端的聚合物在几乎相等的数均分子量。薄层色谱分析表明，终端MHB聚合物与二氧化硅的相互作用是较强的非官能化和羟基封端的聚合物相比。流变学表征表明，在恒定剪切速率下的各种MHB聚合物的熔体粘度是那些非官能化和羟基封端的聚合物的100倍以上。有趣的是，MHB聚合物的熔体粘度比数均分子量为两倍的非官能化聚合物的熔体粘度高。此外，DSC和流变学表征还表明，末端MHB聚合物在熔融状态下形成聚集体而不是简单的二聚体，并且观察到聚集体在80 ℃下完全解离。
The synthesis and characterization of terminal multiple hydrogen-bonded (MHB) polymers, such as poly(styrene) (PS), poly(isoprene) (PI), and microphase separated PS-b-PI block copolymers, possessing controlled molecular weights and narrow molecular distributions are described. Hydroxyl-terminated polymeric precursors were prepared using living anionic polymerization and subsequent quantitative termination with ethylene oxide. MHB polymers were synthesized in a controlled fashion via end-group modification of these well-defined macromolecular alcohols with excess isophorone diisocyanate and subsequent derivatization of the isocyanate-terminated polymeric intermediate with methyl isocytosine. The glass transition temperatures of the terminal MHB polymers were reproducibly higher than both nonfunctionalized and hydroxyl-terminated polymers at nearly equivalent number average molecular weights. Thin-layer chromatography analysis indicated that the interaction of terminal MHB polymers with silica was stronger as compared to both nonfunctionalized and hydroxyl-terminated polymers. Rheological characterization indicated that the melt viscosity at constant shear rate for various MHB polymers was more than 100 times higher than those for nonfunctionalized and hydroxyl-terminated polymers. Interestingly, the melt viscosity of MHB polymers was higher than those of nonfunctionalized polymers with twice the number average molecular weight. In addition, DSC and rheological characterization also suggested that terminal MHB polymers formed aggregates and not simple dimers in the melt state, and the aggregates were observed to completely dissociate at 80 degrees C.