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首页> 外文期刊>RSC Advances >Synthesis and characterization of liquid-crystalline ionomers with pendant cholesteryl pyridinium salt mesogens
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Synthesis and characterization of liquid-crystalline ionomers with pendant cholesteryl pyridinium salt mesogens

机译：侧基胆固醇基吡啶鎓盐液晶元的液晶离聚物的合成与表征

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摘要

Novel chiral liquid-crystalline (LC) bromo-polysiloxanes (IP, IIP and IIIP) were graft copolymerized in a one-step hydrosilylation reaction by use of polymethylhydrogenosiloxane, cholest-5-en-3-ol(3 beta)-10-undecenoate and 4-bromobut-1-ene. A pyridyl-containing LC monomer cholesteryl isonicotinate (CIN) was synthesized and characterized. Some LC ionomers [IP-IIIP-Py][X] (X = Br) were synthesized by use of CIN and the bromo-polysiloxanes. Other LC ionomers [IP-IIIP-Py][X] (X = BF4, PF6, Tf-2 N) were prepared by metathesis of the pyridinium bromides. The chemical structure and liquid-crystalline properties were investigated by various experimental techniques. All the bromo-polysiloxanes display a smectic A (SA) mesophase when they are heated and cooled, while all these LC ionomers show a chiral smectic C (S-C*) phase on heating, and exhibit SA and S-C* phases on cooling. The LC ionomers show a narrower range of LC temperature than the corresponding bromo-polysiloxanes. For the LC ionomers bearing homologous pyridinium cations and different anions, the glass transition temperature, mesophase-isotropic phase transition temperature and LC temperature range tend to reduce, and the spontaneous polarization value increases slightly in the sequence of Br-, BF4-, PF6-, and Tf2N-. Rearrangement of smectic layers due to electrostatic attraction and ion aggregation of cholesteryl pyridinium salt mesogens lead to the formation of the S-C* phase for these LC ionomers.
机译：新型手性液晶（LC）溴代聚硅氧烷（IP，IIP和IIIP）通过使用聚甲基氢硅氧烷，胆甾-5-烯-3-醇（3β）-10-十一碳烯酸酯在一步氢化硅烷化反应中进行接枝共聚和4-溴丁-1-烯。合成并表征了含吡啶基的LC单体胆固醇异烟酸酯（CIN）。通过使用CIN和溴代聚硅氧烷合成了一些LC离聚物[IP-IIIP-Py] [X]（X = Br）。其他LC离聚物[IP-IIIP-Py] [X]（X = BF4，PF6，Tf-2 N）是通过吡啶鎓溴化复分解制备的。通过各种实验技术研究了化学结构和液晶性质。当加热和冷却时，所有溴聚硅氧烷均显示出近晶A（SA）中间相，而所有这些LC离聚物在加热时均显示出手性近晶C（S-C *）相，并在冷却时显示SA和S-C *相。 LC离聚物的LC温度范围比相应的溴代聚硅氧烷窄。对于带有均相吡啶鎓阳离子和不同阴离子的LC离聚物，玻璃化转变温度，中间相-各向同性相转变温度和LC温度范围趋于降低，并且自发极化值按Br-，BF4-，PF6-的顺序略有增加。和Tf2N-。由于静电吸附和胆甾醇基吡啶鎓盐液晶元的离子聚集，近晶层的重排导致这些LC离聚物的S-C *相形成。

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