材料期刊网

本文主要报道了一系列不对称取代的苯并菲丙烯酸酯类盘状液晶中间体化合物的合成及其液晶相行为研究.首先,从单羟基苯并菲类衍生物出发,针对不同长度烷基间隔基体系的反应活性差异,采用不同方法引入可聚合丙烯酸酯基官能团,对亚甲基间隔基数目从0到10的苯并菲丙烯酸酯进行全系列合成,并通过核磁共振波谱(NMR)和质谱(MS)对合成目标产物进行化学结构确认.通过差示扫描量热法(DSC)、偏光显微镜(POM)和小角/广角X射线散射(SAXS/WAXS)表征并分析该系列盘状苯并菲丙烯酸酯中间体的液晶相行为及组装的柱状有序结构.结果表明,大多数己氧基苯并菲类丙烯酸酯中间体只形成结晶;而丁氧基苯并菲类中间体则大都能呈现单向或双向互变型热致六方柱状液晶相,以及一类典型的具有三维(3D)位置有序的六方柱状塑晶相.该类不对称取代的苯并菲丙烯酸酯盘状液晶相态结构与相行为关系的阐明,将对(甲基)丙烯酸酯类可聚合功能性单体的设计合成以及加深对聚合制得侧链盘状液晶聚合物的多级有序相结构的认识和理解具有重要意义.

We present a systematical investigation on the synthesis, molecular characterization and liquid crystalline phase behaviors of a series of triphenylene (TP) acrylate intermediates.Based on different reaction activity of variant length of polymethylene spacer, several synthetic protocols have been successfully employed for introducing an acrylate group to the TP core via polymethylene spacer with the methylene number from 0 to 10.The obtained polymerizable TP acrylate intermediates were confirmed by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS).Furthermore, differential scanning calorimetry (DSC), polarized optical microscopy (POM) and small-and wide-angle X-ray scattering (SAXS/WAXS) were employed to explore the thermotropic liquid crystalline phase behavior and detailed columnar organizations of the series TP intermediates.Most of the TP acrylates with hexyloxy substituents only exhibited crystalline solid phase, while those with butoxy peripheral groups displayed monotropic or enantiotropic hexagonal columnar liquid crystalline mesophases with one example showing three-dimensional (3D) positionally ordered hexagonal columnar plastic phase.Herein the comprehensive synthesis and systematical comparison study on their liquid crystalline phase behaviors of the series discotic TP acrylate intermediates with variant length spacers would be helpful for guiding the design and preparation of other polymerizable functional (meth)acrylate monomers, and also enhance the in-depth understanding of various hierarchical structures of discotic columnar liquid crystalline polymer materials.