MADIX合成的荷电两亲嵌段共聚物PBA-b-PAA的化学分析及水溶液性质
Chemical analysis and aqueous solution properties of Charged Amphiphilic Block Copolymers PBA-b-PAA synthesized by MADIX
摘要：
我们已经链接的结构和在水溶液中的两亲性带电的两嵌段共聚物聚（丙烯酸丁酯）-b-聚（丙烯酸），PBA-b-PAA，通过控制自由基聚合合成，与样品的物理化学特性。尽管产品的缺陷，样品自组装在熔体和水溶液中预测的单分散微相分离理论。然而，PBA核异常大; PBA核的溶胀不是由于AA（Flory参数chiPBA/PAA，在0.25处测定，意味着强分离），而是由于h-PBA均聚物（通过液相色谱法在排阻和吸附转变点LC-PEAT测定含量）。除了通过散射实验检测到的胶束的优势群体之外，毛细管电泳CE分析允许检测另外两个群体，一个是h-PAA，另一个是游离的PBA-b-PAA链，其具有非常短的PBA块并且从不自组装。尽管存在这些游离单聚体，但发现溶液中的自组装不平衡：聚集状态是历史依赖性的，并且数月内胶束之间没有单聚体交换（时间演化SANS）。在20 mN/m下测量的高PBA/水界面张力阻止胶束之间的单聚物交换。PBA-b-PAA溶液体系既不处于热平衡，也不是完全冻结的体系：可能发生单个聚集体的内部分馏。
英文摘要：
We have linked the structural and dynamic properties in aqueous solution of amphiphilic charged diblock copolymers poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA, synthesized by controlled radical polymerization, with the physico-chemical characteristics of the samples. Despite product imperfections, the samples self-assemble in melt and aqueous solutions as predicted by monodisperse microphase separation theory. However, the PBA core are abnormally large; the swelling of PBA cores is not due to AA (the Flory parameter chiPBA/PAA, determined at 0.25, means strong segregation), but to h-PBA homopolymers (content determined by Liquid Chromatography at the Point of Exclusion and Adsorption Transition LC-PEAT). Beside the dominant population of micelles detected by scattering experiments, capillary electrophoresis CE analysis permitted detection of two other populations, one of h-PAA, and the other of free PBA-b-PAA chains, that have very short PBA blocks and never self-assemble. Despite the presence of these free unimers, the self-assembly in solution was found out of equilibrium: the aggregation state is history dependant and no unimer exchange between micelles occurs over months (time-evolution SANS). The high PBA/water interfacial tension, measured at 20 mN/m, prohibits unimer exchange between micelles. PBA-b-PAA solution systems are neither at thermal equilibrium nor completely frozen systems: internal fractionation of individual aggregates can occur.
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