Effects Of Backbone And Mesogenic Structure On The Phase Behaviors Of Mesogen-jacketed Liquid Crystalline Polymers

Polyacrylate side-chain liquid-crystalline polymer, one of the SCLCPs, hasattracted considerable interest in so many fields with great potential application ininformation storage and gas chromatographic analysis.The molecular structure of SCLCPs is consists of four parts: the polymer chain,the flexible spacer, mesogenic unit and the end groups. Depending on the positionwhere the mesogens are linked to the backbone, the mesogen can be eitherlongitudinally or laterally attached into the polymeric system. Thus SCLCPs with alongitudinal connection (end-on) of the mesogen are end-on SCLCPs and those withlateral connection (side-on) are called side-on SCLCPs. It is well-known thatmesogen-jacketed liquid crystal polymers (MJLCPs) have the typical chemicalstructure as side-chain liquid crystal polymers and properties as main-chain liquidcrystal polymers.This paper mainly focuses on studying the effection of polymerbackbone and connection type of mesogens on the liquid crystalline behavior ofpolyacrylates. The works are mainly divided into the following two aspects.Firstly, four kinds of monomers are designed and synthesized with the name of2,5-bis [(p-methoxyphenoxy) carbonyl] benzyl methacrylate),2,5-bis(4’-methoxybenzoyloxy) benzyl methacrylate，2,5-bis [(p-methoxyphenoxy) carbonyl]benzyl acrylate and2,5-bis (4’-methoxybenzoyloxy) benzyl acrylate. The molecularstructure of these monomers is performed with1H NMR and13C NMR. The phasestructures and transition behaviors of the monomers are studied by using differential scanningcalorimetry (DSC) and polarized optical microscope (POM). Through those efforts, we findthat the monomers are thermosensitive liquid crystal except monomer M1and M2, andthe liquid-crystalline behavior of the monomers is depended on the chemical structureobviously. And it is difficult to identify the LC pahse because of the lability ofmonomer M2.Secondly, in this paper a series of polymers with different polymer backbone orlateral substitutent was successfully synthesized by free radical polymerization. Fourkind of polymers are designed and synthesized with the name of poly-(2,5-bis[(p-methoxyphenoxy) carbonyl] benzyl methacrylate), poly-[2,5-bis(4’-methoxybenzoyloxy) benzyl methacrylate]， poly-(2,5-bis [(p-methoxyphenoxy)carbonyl] benzyl acrylate)，poly-[2,5-bis (4’-methoxybenzoyloxy) benzyl acrylate].The sturcture of these polymers is performed with gel permeation chromatography (GPC) and 1H NMR, The phase structures and transition behaviors of the polymers are studied by usingpolarized optical microscope (POM), differential scanning calorimetry (DSC) andthermogravimetric analysis (TGA). The results show that the PM2and PM4are thermotropicliquid crystals, however, PM1and PM3are not. This indicates that the connection typeof mesogens in side-chains will affect the liquid crystallinity of mesogen-jacketed polymersremarkably, however, the changes of main chain is not obviously.