Weakening of Solvation-Induced Ordering by Composition Fluctuation in Salt-Doped Block Polymers
Weakening of Solvation-Induced Ordering by Composition Fluctuation in Salt-Doped Block Polymers
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DOI：
10.1021/acsmacrolett.1c00107
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发表时间：
2021-04-20
影响因子：
7.015
通讯作者：
Qin, Jian
中科院分区：
文献类型：
--
作者：
Kong, Xian;Hou, Kevin Jia-Yu;Qin, Jian
离子掺杂嵌段聚合物的自发有序性受到选择性溶剂化和远程库仑相互作用的影响。最近的研究表明，平均场处理高估了溶剂化引起的有序，需要较大的溶剂化半径来拟合实验相图，这可以通过包括成分波动来缓解。处理这类系统中的成分波动是具有挑战性的，因为需要解决与有序本身耦合的非均匀介电剖面。从最小模型出发，我们建立了盐掺杂嵌段聚合物在有序跃迁附近自由能的Landau-Brazovskii展开式。发现典型的组成波动的波长在盐掺杂时由于库仑相互作用先减小，然后由于离子溶剂化而增大。确定了两种削弱溶剂化增强有序的机制：稳定无序相的brazovskii型成分波动，以及通过单体极化率在色散相互作用中的失配与介电常数之间的耦合。
The spontaneous ordering of block polymers doped with ions is affected by both selective solvation and long-range Coulombic interaction. The mean-field treatment was recently shown to overestimate the solvation-induced ordering, requiring a large solvation radius to fit experimental phase diagrams, which may be relieved by including composition fluctuations. Treating the composition fluctuations in such systems is challenging because of the need of resolving heterogeneous dielectric profile that couples with the ordering itself. Starting from a minimal model, we develop a Landau-Brazovskii expansion for the free energy of salt-doped block polymer near the ordering transition. It is found that the wavelength for typical composition fluctuations first decreases with salt doping, due to Coulombic interaction, then increases due to ionic solvation. Two mechanisms that weaken the solvation-enhanced ordering are identified: the Brazovskii-type composition fluctuation that stabilizes disordered phase, and the coupling between mismatch in dispersion interaction and the dielectric permittivity through monomeric polarizability.