Department of Chemical and Materials Engineering, National Central University, Taoyuan 32001, Taiwan.
National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
Langmuir. 2022 May 17;38(19):5987-5995. doi: 10.1021/acs.langmuir.2c00041. Epub 2022 May 4.
This study aims to quantitatively investigate the effect of water content on the self-assembly behavior of polystyrene--poly(ethylene oxide) (PS--PEO) in tetrahydrofuran/water cosolvents by small-angle X-ray scattering. PS--PEO chains preferentially form fractal aggregates at a dilute concentration in neat tetrahydrofuran (THF). By adding a small amount of water into THF, PS--PEO forms gelled networks. The gelled networks have correlated inhomogeneities, which were generated through mesophase separation. These gelled networks are not present when PS--PEO is dissolved in THF/methanol and THF/ethanol cosolvents. The substitution of water with 12 M HCl reduces the viscosity of the gelled networks. Those results indicate that the gelled networks of PS--PEO need hydrogen bonds formed from surrounding water molecules to be bridging agents, which connect different PEO block chains together. Upon increasing the water content in THF/water cosolvents, dispersed micelles with a core-shell conformation or aggregated micelles preferentially coexist with fractal aggregates.
本研究旨在通过小角 X 射线散射定量研究水含量对聚苯乙烯-聚（氧化乙烯）（PS-PEO）在四氢呋喃/水共溶剂中自组装行为的影响。在纯四氢呋喃（THF）中，PS-PEO 链在稀浓度下优先形成分形聚集。通过向 THF 中加入少量水，PS-PEO 形成凝胶网络。凝胶网络具有相关的非均相性，是通过中间相分离产生的。当 PS-PEO 溶解在 THF/甲醇和 THF/乙醇共溶剂中时，不会出现这些凝胶网络。用 12 M HCl 代替水会降低凝胶网络的粘度。这些结果表明，PS-PEO 的凝胶网络需要由周围水分子形成的氢键作为桥联剂，将不同的 PEO 链连接在一起。随着 THF/水共溶剂中水含量的增加，具有核壳结构的分散胶束或聚集胶束与分形聚集物优先共存。
