Synthesis And Properties Of Chiral Liquid Crystals Based On Menthol

Chiral liquid crystals have attracted more and more attention at present. Molecular chirality has a particularly remarkable influence on the macroscopic physical properties of liquid crystal systems. Many physical properties of liquid crystals depend on chir- ality, e.g., certain linear and nonlinear optical properties, the occurrence of ferro-, ferri-, antiferro- and piezo-electric behavior, the electroclinic effect, and even the appearance of new phases. In addition, the majority of optical applications of liquid crystals is due to chiral structures, namely the ther-mochromic effect of cholesteric liquid crystals, the rotation of the plane of polarization in twisted nematic liquid crystal displays, and the ferroelectric and antiferroelectric switching of smectic liquid crystals. In this thesis, we synthesized a series of chiral liquid crystal monomers and side chain liquid crystalline polymers containing menthyl, and their structures and liquid crystal behaviors were identified.This thesis is divided into three parts. In the first part, we synthesized a series of chiral liquid crystal monomers, (PBnMB:PB4MB?PB5MB?PB6MB?PB8MB. PB10MB), using menthyl group as chiral primitives,-/-ArCOOAr-Ar-/- as the rigid mesogenic core, pentyloxy group as the terminal group. The effect of the length of dicarboxylic acid spacer on liquid crystal properties was discussed. During the heating process, liquid crystal monomers PB4MB. PB5MB present oily streak texture, PB6MB?PB8MB?PB10MB show oily streak texture and fan-shaped texture; During the cooling process,the monomer PB4MB show blue phase and focal conic texture, monomers PB5MB?PB6MB?PB8MB present focal conic and fingerprint texture, PB10MB reveals fingerprint and schlieren texture.In the second part, we synthesized a series of chiral liquid crystal monomers, using menthyl group as chiral primitives,-/-ArCOOAr-Ar-/- as the rigid mesogenic core, alkoxyl group as the terminal group. The effect of the length of alkoxyl group on liquid crystal properties was discussed. This series of liquid crystal monomers present oily streak texture during the heating process?During the cooling process 4MOBnB (n= 1-4)show blue phase and focal conic texture, and 4MOBnB (n=5-18) present blue phase, focal conic and schlieren texture.In the third part, we synthesized two chiral liquid crystal monomers (M1, M2) using menthyl group as chiral primitives, a reactive alkene group as end group. A series of P1?P7 polymers were prepared by graft polymerization using silicone oil as backbone. During the heating process, P1?P5 present oily streak texture,and P6 shows schlieren texture. During the cooling process, P6 reveals focal conic texture, while P3?P5 show blue phase and focal conic texture. P7 presents grandjean and fan-shaped texture during the cooling process?...