聚苯乙烯-丙烯酸嵌段共聚物在不同pH值和Ca2+浓度下的胶束行为

近年来, 对具有纳米尺寸的聚合物自组装结构的研究日益增多. 其中, 嵌段共聚物在选择性溶剂中的胶束行为研究得最为广泛和深入1~5]. 纳米胶束表现出诸多常规尺寸材料所不具备的特殊性能, 在材料化学、生物医学以及环境科学等领域有广阔的应用前景. Webber等6]对聚丙烯酸和聚苯乙烯接枝共聚物的研究发现, 聚合物的接枝率和聚合物浓度以及溶液离子强度对胶束结构有影响; Eisenberg等1,7]对不同嵌段比例的苯乙烯-丙烯酸嵌段共聚物的自组装行为进行研究发现, 不同嵌段比例所对应的胶束结构不同. 胶束形成的环境对胶束的形成与稳定性的影响是人们研究的重点. 本文报道了聚苯乙烯-丙烯酸嵌段共聚物在水中的胶束行为, 着重讨论了溶液pH值和钙离子浓度对聚丙烯酸链段相互作用的影响.

Micelles Behavior of P(Styrene-b-acrylic acid) Block Copolymer at Different pH and Calcium Ion Concentration

The micelles behavior of amphiphilic block copolymer P(Styrene\|b\|acrylic acid), in aqueous solvent was studied by dynamic light scattering and TEM techniques. The diameters of micelle decreased and then increased with the decrease of the pH of the solution, and the similar phenomenon was also detected with the increase of the concentration of the calcium ion. Without added acid, the micelles were small spheres of low polydispersity with an average diameter 48 nm. When the value of pH was less than 2, the micelles were unstable. It was found that the Ca\+\{2+\} was linked with the carboxyl in the same micelle when the concentration of the CaCl\-2 was less than 0\^2 mg/mL. The diameter of micelle was smaller than the one without Ca\+\{2+\}. The Ca\+\{2+\} was linked with the carboxyl between the different micelles when the concentration of the CaCl\-2 was more than 0\^5 mg/mL and the micelle was unstable. The diameters of micelles(from 37 nm to 100 nm) can be controlled by adding an appropriate concentration of CaCl\-2 between 0\^2\_0\^5 mg/mL.