Synthesis And Characterization Of Liquid Crystalline Polymers And Elastomers Containing Fluorinated Substitution Groups

It is fluorine’s small size,large electronegativity, low polarizability, and large fluorine-fluorine repulsion that lead to many interesting properties of fluoropolymers. Side-chain and terminal fluorinated compounds can raise the solubility of other liquid crystals(LCs) in mix LCs due to fluorine’s greasy solubility.In this dissertation, five monomers containing M1,M2,M3,M5,M6were synthesized. There are4-allyloxy-benzoic acid4’-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8pentadecafluoro-octanoyloxy)-biphenyl-4-ylester (M1)、4-Undec-10-enoyloxy-benzoicacid4’-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-octanoyloxy)-biphenyl-4-yl ester(M2)、cholesteryl4-allyloxy benzoic acid (M3)、hexahydrofuro[3,2-b]furan-3,6-diyl bis(4-(allyloxy)benzoate)(M5)、hexahydrofuro-[3,2-b]furan-3,6-diyl diundec-10-enoate(M6).Tow fluorinated monomers which are very innovative named M1and M2. M3is chiral liquid crystalline monomer. M5and M6are non-liquid crystal Crosslinker. Different kinds of mesogenic monomers w-ere grafted to linear polymethylhydrogensiloxanes. So four series of liquid crystalline polymers(LCPs) with different chemical structures and characters were synthesized.The structures of the four obtained liquid crystalline monomers were analyzed and proved by FT-IR spectroscopy and1H nuclear magnetic resonance (’H NMR). Results of specific rotation analysis(SRA) showed that chiral monomers M1,M2and M3were all optical active. The phase transition temperature, enthalpy increment and mesogenic texture were studied with differential scanning calorimetry(DSC) and polarized optical microscopy (POM).Results of DSC and POM indicated that fluorinated monomer M1and M2monomer was typical liquid smectic crystal and had many advantages such as good thermal stability, wide mesomorphic temperature range and so on. M3was typi-cal liquid cholesteric phase.Polymers P1, P3, P4were cholesteric liquid crystals during heating process. Polymers of these three P1,P2,P4series were all optical active, and had good thermal stability.