Self-assembly of highly asymmetric, poly(ionic liquid)-rich diblock copolymers and the effects of simple structural modification on phase behaviour
Self-assembly of highly asymmetric, poly(ionic liquid)-rich diblock copolymers and the effects of simple structural modification on phase behaviour
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DOI：
10.1039/c8py01414k
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发表时间：
2019-02-14
影响因子：
4.6
通讯作者：
Bailey, Travis S.
中科院分区：
文献类型：
--
作者：
May, Alyssa W.;Shi, Zhangxing;Bailey, Travis S.
合成了一系列可热处理的相分离二嵌段共聚物，这些共聚物是通过苯乙烯和苯乙烯离子液体（IL）单体与各种烷基咪唑鎓取代基的连续 ATRP 制成的，以覆盖各种体积分数，尤其是相图富含 IL 一侧的体积分数。小角 X 射线散射 (SAXS) 分析用于确认熔融态（和玻璃态）相行为，其中观察到所有四种经典的平衡二嵌段共聚物形态——体心立方球体 (S-BCC)、六方堆积圆柱体 (Hex)、片晶 (Lam)，以及值得注意的双连续陀螺仪 (Gyr)。发现这些 PS-PIL 二嵌段共聚物在 PIL 嵌段内具有高度的构象不对称性和/或静电内聚力，这通过边界落在 f(PIL) = 0.31 和 0.55 之间的 Lam 相窗口的移动来突出。烷基的变化似乎会影响系统类Flory相互作用参数chi(PS/PIL)的强度，使得咪唑鎓IL取代基上的甲基被正丁基简单取代导致出现（众所周知的偏析敏感）Gyr相，取代了甲基取代的咪唑鎓二嵌段共聚物相图中持续共存的Lam和Hex。
A series of thermally processable, phase-separating diblock copolymers made via sequential ATRP of styrene and styrenic ionic liquid (IL) monomers with various alkyl imidazolium substituents were synthesized to cover a wide range of volume fractions, most notably those on the IL-rich side of the phase diagram. Small-angle X-ray scattering (SAXS) analysis was used to confirm melt-state (and glassy state) phase behavior in which all four classic equilibrium diblock copolymer morphologies-body-centered cubic spheres (S-BCC), hexagonally packed cylinders (Hex), lamellae (Lam), and notably, bicontinuous gyroid (Gyr)-were observed. These PS-PIL diblock copolymers were found to have a high degree of conformational asymmetry and/or electrostatic cohesion within the PIL block, highlighted by the shift of the Lam phase window with boundaries falling between f(PIL) = 0.31 and 0.55. Variation of the alkyl group appeared to influence the strength of the Flory-like interaction parameter of the system, chi(PS/PIL), such that simple substitution of methyl by n-butyl on the imidazolium IL substituent resulted in the emergence of the (notoriously segregation-sensitive) Gyr phase, superseding the persistent coexistence of Lam and Hex in the methyl-substituted imidazolium diblock copolymer phase diagram.