Synthesis And Properties Of Multi-arm Ester Liquid Crystal Macromolecules Centered On Cholic Acid

With the in-depth exploration of liquid crystal chemistry,the design and synthesis of a new class of liquid crystal compounds and liquid crystal polymers have become the mainstream research direction.The multi-arm liquid crystal compound is a novel liquid crystal material in which plurality of liquid crystal arms are connected to a central atom or a group.The multi-arm liquid crystal compound has excellent liquid crystal properties and is widely used.As a new liquid crystal compound,the novel ester liquid crystal compound centered on cholic acid is different from the traditional rod-like liquid crystal compound.With the change of the terminal end group and the length of the flexible chain,the liquid crystal compound show a colorful liquid crystal phase.On the basis of reviewing relevant literatures at home and abroad,this paper designed and synthesized a variety of long-chain ester liquid crystal arms,and combined them with cholic acid to prepare multi-arm ester liquid crystal macromolecules by esterification reaction.At the same time,a multi-arm liquid crystal momer centered on cholic acid was designed and synthesized,and it was combined with a flexible polysiloxane main chain and a cyclic polysiloxane main chain to prepare a series of liquid crystal polymers.This paper is divided into the following three parts:In the first part,this paper designed and synthesized five ester monophenols with different terminal groups,benzoyloxy hydroquinone monophenol(A1),4-methoxybenzoyloxy hydroquinone monophenol(A2),4-chlorobenzoyloxy hydroquinone monophenol(A3),4-ethoxybenzoyloxy hydroquinone mophenol(A4)and 4-nitrobenzoyloxy Hydroquinone mophenol(A5),and combined them with adipic acid to prepare five liquid crystal arms with different terminal grounps,benzoyloxy-4-phenoxycarbonyl valeric acid(B1),4-methoxy Benzoyloxy-4-phenoxy-carbonyl valeric acid(B2),4-chlorobenzoyloxy-4-phenoxycarbonyl valeric acid(B3),4-ethoxybenzoyloxy 4-phenoxycarbonyl valeric acid(B4)and 4-nitrobenzoyloxy-4-phenoxycarbonyl valeric acid(B5).And finally these liquid crystal arms were connected with cholic acid to prepare three-arm liquid crystal compounds(C1-C5)and four-arm liquid crystal compounds(D1-D5).The FT-IR analysis showed that the synthesized compounds were structurally compatible with the molecular design.The liquid crystal properties of the compounds were tested using DSC and POM.The results showed that the four-arm liquid crystal compounds D2 and D4 were thermotropic tautomeric liquid crystal compounds,and the liquid crystal phase ranges from 45 to 3? during the heating process,and the liquid crystal phase ranges from 90 to 113? during the cooling process.The four-arm liquid crystal compounds D3 and D5 were thermotropic single-neutral phase liquid crystal compound,and the D3 s liquid crystal phase range was 45.8? during the heating process,and the D5's liquid crystal phase range was 64.7? during the cooling process.The four-arm ester compound D1 had no liquid crystallinity during heating and cooling process.When the chain lengths of the multi-arm ester liquid crystal macromolecules are the same but the terminal groups are different,if the liquid crystal compound has a substituent of an electron-donating group,it has a relatively wide liquid crystal region.The electron-donating group is favorable for the formation of liquid crystal phase,when the terminal group is the ethoxy group,the liquid crystal interval is the widest.In the second part,this paper designed and synthesized the ester mophenol,4-methoxybenzoyloxy hydroquinone mophenol(A2),and combined it with succinic anhydride,adipic acid,suberic acid and azelaic acid to prepare four liquid crystal arms with different chain length,4-methoxybenzoyloxy-4-phenoxycarbonylpropionic acid(B6),4-methoxybenzoyloxy-4-phenoxycarbonyl valeric acid(B2),4-methoxy Benzoyloxy-4-phenoxycarbonyl heptanoic acid(B7),4-methoxybenzoyloxy-4-phenoxycarbonyl decanoic acid(B8).And finally these liquid crystal arms were connected with cholic acid to prepare three-arm liquid crystal compounds(C2?C6-C8)and four-arm liquid crystal compounds(D2?D6-D8).The FT-IR analysis showed that the synthesized compounds were structurally compatible with the molecular design.The liquid crystal properties of the compounds were tested using DSC and POM.The results showed that the four-arm liquid crystal compounds D2,D7 and D8 were thermotropic tautomeric liquid crystal compounds,and the liquid crystal phase ranges from 51 to 83? during the heating process,and the liquid crystal phase ranges from 90 to 110? during the cooling process.The four-arm ester compound D6 had no liquid crystallinity during heating and cooling process.When the terminal group of the multi-arm ester liquid crystal macromolecules is the same but the chain length is different,the longer the chain length is,the liquid crystal interval is wider.In the third part,this paper designed and synthesized the multi-arm liquid crystal momer MD centered on cholic acid,and connected it with polymethylhydrogensiloxane(PMHS)and cyclic polymethylhydrogensiloxane to prepare a series of liquid crystal polymers PL and PH.The FT-IR analysis showed that the synthesized compounds were structurally compatible with the molecular design.The liquid crystal properties of the compounds were tested using DSC and POM.The results showed that the liquid crystal momer MD was a thermotropic tautomeric liquid crystal compound,and the liquid crystal phase ranges was 31.6? during the heating process,and the liquid crystal phase ranges was 72.8? during the cooling process.The polymer PL compounds were thermotropic tautomeric liquid crystal compounds,and the liquid crystal phase ranges from 31 to 47? during the heating process,and the liquid crystal phase ranges from 62 to 89? during the cooling process.The polymer PH compounds had no liquid crystallinity during heating and cooling process.