To achieve large spontaneous polarization for ferroelectric liquid crystalline polymers, we have designed a series of mesogen-free isotactic polyethers with sulfonylated side chains. Different from prior studies using linear alkyl side chains, in this work a methyl branch was implemented in the alkyl side chains of the chiral polyethers. As a result of the continuous twist from the methyl branches and strong dipole-dipole interactions among neighboring sulfonyl groups, a helical chain conformation with tilted side chains was achieved. When the branched side chains were short (e.g., C5) and double chirality existed in both the main chain and side chains, a crystalline structure was obtained. When the branched side chains were long (e.g., ≥ C8) and single chirality existed in the main chain, an ordered hexagonal columnar liquid crystalline phase was induced. Their high-field dielectric property was studied by electric displacement-electric field (D-E) loop tests; however, no ferroelectric behavior was observed up to 200 MV/m. It was considered that the dipole-dipole interaction among neighboring sulfonyl groups in the helical chains was too strong to allow easy ferroelectric flipping.

为了实现铁电液晶聚合物的大自发极化，我们设计了一系列具有磺酰化侧链的无介晶等规聚醚。与先前使用线性烷基侧链的研究不同，在这项工作中，在手性聚醚的烷基侧链中实施了甲基支链。由于甲基支链的连续扭曲和相邻磺酰基之间强烈的偶极-偶极相互作用，实现了具有倾斜侧链的螺旋链构象。当支链侧链较短（如C5）且主链和侧链均存在双手性时，获得晶体结构。当支链较长（如≥C8）且主链存在单一手性时，诱导出有序的六方柱状液晶相。通过电位移-电场（DE）回路试验研究了它们的高场介电性能；然而，在高达 200 MV/m 时没有观察到铁电行为。认为螺旋链中相邻磺酰基之间的偶极-偶极相互作用太强而不能容易地进行铁电翻转。