Zhang Bo, Zheng Caini, Sims Michael B, Bates Frank S, Lodge Timothy P
ACS Macro Lett. 2021 Aug 17;10(8):1035-1040. doi: 10.1021/acsmacrolett.1c00393. Epub 2021 Jul 23.
A series of symmetric poly[(oligo(ethylene glycol) methyl ether methacrylate--oligo(ethylene glycol) propyl sodium sulfonate methacrylate)]--polystyrene (POEGMA-PS) diblock copolymers were synthesized as a model system to probe the effect of charge fraction on the phase behavior of charged-neutral single-ion conducting diblock copolymers. Small-angle X-ray scattering (SAXS) experiments showed that increasing the charge fraction does not alter the ordered phase morphology (lamellar) but increases the order-disorder transition temperature () significantly. Additionally, the effective Flory-Huggins interaction parameter (χ) was found to increase linearly with the charge fraction, similar to the case of conventional salt-doped diblock copolymers. This indicates that the effect of counterion solvation, attributed to the significant mismatch between the dielectric constant of each block, provides the dominant effect in tuning the phase behavior of this charged diblock copolymer. We therefore infer that electrostatic cohesion (local charge ordering induced by Coulombic interactions), which is predicted to suppress microphase separation and lead to asymmetric phase diagrams, only plays a minor role in this model system.
合成了一系列对称的聚[（聚乙二醇甲醚甲基丙烯酸酯 - 聚乙二醇丙基磺酸钠甲基丙烯酸酯）] - 聚苯乙烯（POEGMA - PS）二嵌段共聚物，作为一个模型系统来探究电荷分数对带电 - 中性单离子导电二嵌段共聚物相行为的影响。小角X射线散射（SAXS）实验表明，增加电荷分数不会改变有序相形态（层状），但会显著提高有序 - 无序转变温度（）。此外，发现有效弗洛里 - 哈金斯相互作用参数（χ）随电荷分数线性增加，这与传统盐掺杂二嵌段共聚物的情况类似。这表明，由于每个嵌段介电常数的显著不匹配而导致的抗衡离子溶剂化效应，在调节这种带电二嵌段共聚物的相行为中起主导作用。因此我们推断，预计会抑制微相分离并导致不对称相图的静电凝聚（由库仑相互作用引起的局部电荷有序），在这个模型系统中仅起次要作用。
