稳态和动态荧光研究疏水缔合共聚物P(AM/POEA)的自缔合行为和聚集体

Steady-state and Dynamic Fluorescence Studies on Self-associating Behavior and Aggregate of Hydrophobically Associating Copolymer P(AM/POEA)

应用稳态和动态荧光光谱方法 ,包括荧光探针、标记荧光和荧光淬灭等研究了共聚物P(AM/POEA)在水溶液中的自缔合性质 .这种共聚物由丙烯酰胺 (AM)和少量疏水单体 2 苯氧乙基丙烯酸酯 (POEA)组成 .实验结果表明这类共聚物的自缔合行为和聚集体结构主要取决于聚合物的链结构和浓度 .由胶束共聚合方法得到具有多嵌段结构的共聚物 ,它们容易发生疏水缔合 ,并产生很强的增粘作用 ,而由普通共聚合方法得到的无规共聚物却没有这些性质 .同时这类聚合物的缔合类型及其增粘能力也直接与共聚物中的疏水体含量相关 ,随疏水体含量增加 ,由于分子间和分子内缔合的竞争 ,出现粘度先增后降的现象 .在荧光研究的基础上提出了多分子聚合物聚集体的结构模型 ,它随聚集体浓度增加 ,进一步形成多联聚集体和网状结构 .同时还观察到聚集体中疏水体有序排列现象 .

The different steady-state and dynamic fluorescence methods, including luminescence probe, label fluorescence and fluorescence quenching measurements, have been used to investigate the association properties of the copolymer P(AM/POEA), composed of acrylamide (AM) and a, small amount of 2-phenoxyethyl acrylate (POEA) (x(POEA) less than or equal to 0.01) as hydrophobe in aqueous solution. The experimental results show that the self-associating behavior and aggregate structure of the copolymer are significantly dependent on their chain structure and concentration. The copolymers with the multi-blocky structure obtained by micellar copolymerization exhibit a large thickening property due to the intermolecular hydrophobical association, but that does not occur in the case of the random copolymers prepared by the conventional copolymerization. The association type and the thickening ability of the copolymers were found to directly related to the hydrophobe content of copolymer. With raising hydrophobe content the reduced viscosity firstly increases and then decreases due to the competition between intra- and inter-chain associations. Based on the fluorescence studies the mufti-polymeric aggregate structure model was suggested, which further grows into cross-linked mufti-aggregate and network as polymer aggregate concentration is increased. The ordered alignment phenomena of hydrophobe in the aggregate were also observed.