A triblock copolymer with hydrophobic end blocks and a polyampholytic middle block is investigated in a mixture of water and acetone with a focus on the dependence of the rheological properties and of the micellar structure and correlation on the content of acetone. The polymer under study is PMMA86-b-P(DEA190-co-MAA96)-b-PMMA86, where PMMA stands for poly(methyl methacrylate) and P(DEA-co-MAA) for poly(2-(diethylamino) ethyl methacrylate-co-methacrylic acid). The pH is chosen at 3. Rheological measurements reveal a transition from a viscoelastic solid over a viscoelastic liquid to a freely flowing liquid upon addition of 5 or 10 wt% of acetone to a 3 wt% aqueous polymer solution, respectively. Using small-angle neutron scattering on 0.5 wt% polymer solutions in water/acetone with the content of the latter ranging between 0 and 30 wt%, significant structural changes are observed as well, such as a decrease of the distance between the PMMA cross-links and of the size of the network clusters upon increasing acetone constant. These changes are attributed to the reduction of the dielectric constant by the addition of the cosolvent acetone, enhancing the flexibility of the middle blocks and their tendency to backfolding, as well as to the decrease of the solvent selectivity, inducing significant exchange rate enhancement of the core-forming PMMA blocks.

中文翻译：

---

助溶剂对遥爪聚两性电解质流变特性和自组装结构的影响

在水和丙酮的混合物中研究了具有疏水性末端嵌段和多两性中间嵌段的三嵌段共聚物，重点是流变特性和胶束结构的依赖性以及与丙酮含量的相关性。正在研究的聚合物是 PMMA86-bP(DEA190-co-MAA96)-b-PMMA86，其中 PMMA 代表聚（甲基丙烯酸甲酯）和 P（DEA-co-MAA）代表聚（2-（二乙氨基）甲基丙烯酸乙酯-co -甲基丙烯酸）。pH 选择为 3。流变学测量表明，在分别将 5 或 10 重量％的丙酮加入到 3 重量％的聚合物水溶液中时，从粘弹性固体上的粘弹性液体转变为自由流动的液体。在水/丙酮中 0.5 wt% 聚合物溶液上使用小角中子散射，后者的含量在 0 到 30 wt% 之间，还观察到显着的结构变化，例如随着丙酮常数的增加，PMMA 交联之间的距离和网络簇大小的减小。这些变化归因于通过添加共溶剂丙酮降低了介电常数，增强了中间嵌段的柔韧性和它们的回折倾向，以及溶剂选择性的降低，导致显着的交换率增强形成核心的 PMMA 块。