Synthesis And Properties Of Liquid Crystal Polymer With Ester Group As The Central Bridge

As a functional soft material with both liquid phase fluidity and solid phase anisotropy,the liquid crystal phase is widely used in thin film materials,optoelectronic materials,biomedicine and other fields due to its excellent orientation,high strength and excellent heat resistance.Medical supplies and other fields have a wide range of applications.In this paper,we designed and synthesized two kinds of liquid crystal polymers with ester group as the central bridge,and tested their liquid crystal properties and applied them respectively.The main contents of this article are as follows:(1)First,mesogens were synthesized using 4-Hydroxybenzyl cyanide,3-bromo-1-propene,4-Hydroxybenzaldehyde and cholesteryl succinate containing ester groups,and then the mesogens were grafted onto2,4,6,8-tetramethylcyclotetrasiloxane(CMHS)to obtain side-chain liquid crystal polymers(SC-LCPs)with ester groups as central bridge bonds.Through various characterization methods,it was found that the introduction of ester groups significantly reduced the glass transition temperature of SC-LCPs and broadened their liquid crystal range,improving the selectivity of the application ambient temperature conditions.The introduction of ?-cyanostilbene derivatives endowed SC-LCPs with aggregation-induced emission effect,which laid the foundation for their future applications in biomedicine,fluorescent probes,etc.(2)Using D-camphoryl chloride,terephthaloyl chloride and hydroquinone as mesogens,and 2,3-dibromosuccinyl chloride as flexible spacer,the main-chain liquid crystal polymers(MC-LCPs)with ester group as the central bridge was prepared by esterification.By grafting triphenylphosphine onto the MC-LCPs,the main-chain ester ionic liquid crystal polymers(MC-ILCPs)with triphenylphosphine as the cation group and bromide ion as the anion group were successfully synthesized,and then,by replacing the anion groups of MC-ILCPs,other anions(hexafluorophosphate,tetrafluoroborate,trifluoroacetate,p-toluenesulfonate,superphosphate)were used as anion groups for MC-ILCPs was successfully synthesized.Through various characterization methods,it can be found that the introduction of ester groups makes MC-LCPs have a wider liquid crystal interval,and the introduction of cationic groups reduces the glass transition temperature of the polymer.Due to the introduction of quaternary phosphonium ions,MC-ILCPs not only have excellent liquid crystal properties,but also have great application potential in antibacterial properties.In this chapter,the antibacterial properties of main-chain ester ionomers are studied,and it is confirmed that the antibacterial activity of triphenylphosphine can be effectively combined with the excellent orientation of liquid crystal polymers,which lays a solid foundation for its future application as antibacterial materials.