Controlling Water Content and Proton Conductivity through Copolymer Morphology
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- 作者：Rasoul Narimani ; Ami C. C. Yang ; Emily M. W. Tsang ; Laurent Rubatat ; Steven Holdcroft ; Barbara J. Frisken
- 刊名：Macromolecules
- 出版年：2013
- 出版时间：December 23, 2013
- 年：2013
- 卷：46
- 期：24
- 页码：9676-9687
- 全文大小：543K
- ISSN：1520-5835
文摘
To investigate relationships between morphology and proton conductivity in ionic copolymer membranes, we have studied two series of fluorous copolymers bearing polystyrene grafts sulfonated from 0 to 100%. Small-angle X-ray and neutron scattering experiments reveal a disordered, partially phase-separated system consisting of fluorous domains in a partially sulfonated polystyrene matrix with aggregation of ion-rich domains within the matrix. The size of the fluorous domains depends on graft density, and their packing depends on the graft chain length. The spacing of the ion-rich domains is remarkably independent of either graft chain length or charge content. We find that the samples with lower graft density, which are partially crystalline, develop a less-ordered morphology with a lower degree of phase separation. The partially crystalline samples swell less and have a slightly lower conductivity at similar water content; the lower conductivity is attributed to a more tortuous conducting phase.