Synergistic Increase in Ionic Conductivity and Modulus of Triblock Copolymer Ion Gels

Ion gels formed with ABA triblock polymers and ionic liquids (IL) have recently attracted significant attention. Because of their high ionic conductivity, high capacitance, and good mechanical integrity, ion gels prepared from triblock polymers of polystyrene-b-poly(methyl methacrylate)-b-polystyrene (SMS) and polystyrene-b-poly(ethylene oxide)-b-polystyrene (SOS) and an IL 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) have been successfully applied as the dielectric layer in thin film transistors. However, water absorption can negatively affect the stability of the dielectric layer and lead to electrical breakdown. Consequently, the preferred polymer of these two is SMS. However, the high glass transition temperature (T-g) of PMMA limits the usable SMS polymer concentration in order to ensure comparable ionic conductivity to that of SOS ion gel; this constraint limits the modulus of the gel to about 10(3) Pa. In this work, we developed a new ABA triblock ion gel system using poly(ethyl acrylate) (PEA) as a low T-g and hydrophobic midblock. The low T-g of the midblock ensures the ionic conductivity of the resulting ion gels is comparable to that of SOS ion gels at polymer concentrations up to 50 wt %, which is a significant improvement relative to the currently used SMS ion gels. Additionally, by decreasing the size of the midblock at constant polymer concentration, the modulus and ionic conductivity of the ion gels increase synergistically. This interesting and counterintuitive effect reflects the concurrent increase in the number density and chain stretching of midblocks, accompanied by a net reduction in midblock concentration within the conducting phase. We demonstrate that electrolyte gated transistors (EGTs) made with SEAS ion gels have improved stability under ambient humid conditions in comparison to those made with SOS ion gels.

用ABA三嵌段聚合物和离子液体（IL）形成的离子凝胶最近引起了极大的关注。由于它们具有高离子电导率，高电容和良好的机械完整性，因此由聚苯乙烯-B-聚合物（甲基丙烯酸甲酯）的三嵌段聚合物制备的离子凝胶-b-丙烯酸酯（SMS）和聚苯乙烯-B-二聚体（乙烯氧化物）-b - 聚苯乙烯（SOS）和IL 1-乙基-3-甲基咪唑唑烷BIS（三氟甲基磺酰基）酰亚胺（[EMI] [TFSI]）已成功地用作薄膜晶体管中的介电层。然而，吸水会对介电层的稳定性产生负面影响，并导致电衰竭。因此，这两个的首选聚合物是SMS。但是，PMMA的高玻璃过渡温度（T-G）限制了可用的SMS聚合物浓度，以确保与SOS离子凝胶的离子电导率相当；这种约束将凝胶的模量限制在大约10（3）pa中。在这项工作中，我们使用聚（丙烯酸乙烯酸乙烯酸乙酯）（PEA）（pea）开发了一种新的ABA三嵌段离子凝胶系统，为低T-G和疏水性中间机。中间块的低T-G确保所得离子凝胶的离子电导率可与高达50 wt％的聚合物浓度下的SOS离子凝胶相当，这是相对于当前使用的SMS离子凝胶的显着改善。另外，通过在恒定聚合物浓度下减小中间块的大小，离子凝胶的模量和离子电导率协同增加。这种有趣且违反直觉的效果反映了中间块的数量密度和链伸展的同时增加，并伴随着导电阶段中屏障浓度的净降低。我们证明，与SOS离子凝胶相比，在环境潮湿条件下，用海凝胶制成的电解质门控晶体管（EGT）提高了稳定性。