芳香酯类三臂液晶化合物的合成与表征

以间苯三酚为中心,ω 4 (对烷氧基苯甲酰氧基)苯氧甲酰基]戊酸为液晶基元,通过酯化反应合成了芳香酯类三臂液晶化合物·这是一类不同于传统棒状及盘状液晶分子的新型结构液晶化合物·通过红外光谱(IR)、核磁共振谱(1HNMR)对其分子结构进行表征·采用差示扫描量热(DSC)、偏光显微分析(POM)、热重分析(TG)等手段对其液晶性能及热稳定性进行研究·结果表明,此类三臂液晶化合物符合分子设计,热稳定性好,5%热失重温度高于340℃,液晶区间随着分子中末端烷基链的加长而增宽,升、降温过程中均呈现丝状织构,属互变向列相液晶·

Synthesis and Mesomorphic Properties of Three-Armed Liquid Crystals Containing Aromatic Esters

A series of novel three-armed liquid crystals based on 1,3,5-trihydroxybenzene as a core and tw-4-(p-alkoxybenzoloxy)phenoxycarbonyl]valeric acid as mesogenic arms were synthesized by aromatic esterification. They are a new kind of liquid crystals differing from conventional rod-like or discotic molecules. Their chemical structures were confirmed by FTIR and ¹HNMR spectra and their mesomorphic phase behavior was investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and thermograrimetric analyzer (TG). The results showed that the three-armed liquid crystals exhibit broad range of liquid crystalline phase at moderate temperature, and the mesomorphic ranges (Δt) broadens with increasing terminal alkyl chains. The temperatures at which the weight loss is up to 5% is higher than 340 t, which revealed that the synthesized three-armed liquid crystals are of high thermal stability. Threadlike texture, typical of nematic phase can be observed in the liquid crystalline state during heating/cooling process.