Synthesis And Properties Of Multiple Chiral Liquid Crystal Materials 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,(MnEB:M4EB,M5EB,M6EB,M8EB,M9EB,M10EB),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 M4EB,M5EB,M6EB present oily streak texture,M8EB,M9EB,show oily streak texture and Falseisotropic phasetexture,M10EB show focal conic,Falseisotropic phasetexture and a new texture.of chiral smectic phase,;During the cooling process,the monomer M4EB show blue phase and focal conic texture,M5EB monomersshow focal conic texture,M6EB,M8EB,M9EB,M10EB show focal conic,Falseisotropic phasetexture and a new texture of chiral smectic phase.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.During the heating process,This series of liquid crystal monomers present oily streak texture during the heating process.During the cooling process,5MOBmB(n=1,2,3,4)show Fingerprinttexture,5MOBmB(n=5,6,7,8,9,10,12,14)show two different Fingerprinttexture of chiral smecticCandcholesteric phase,5MOBmB(n=16,18)present Fingerprinttexture of chiral smecticC phase.In the third part,we synthesized a series of chiral liquid crystal monomers,using menthyl group as chiral primitives,-/-ArCOOAr-Ar-/-as the rigid mesogenic core,Acyloxyl group as the terminal group.The effect of the length of alkoxyl group on liquid crystal properties was discussed.During the heating process,5MOBnB(n=7,8,9,10,12,14,16,18)show focal conic texture of chiral smectic C phase.During the cooling process,5MOBnB(n=2-16)show focal conic texture of chiral smectic C phase,5MOBnB(n=2,3,4,5,6,7,8,10)show focal conic texture of cholesteric phase,5MOBnB(n=9,12,14,16)show fingerprint textures of cholesteric phase.