Design,synthesis And Properties Investigation Of Photoreactive Fan-shaped Liquid Crystal Oligomers

Membrane separation have been widely used in biochemistry,pharmaceuticals,food,water treatment and other fields.An ideal nanoporous membrane is usually consisted of a thin film with physically continuous,vertically aligned nanopores that display a narrow pore size distribution.However,the current state of the art departs considerably from these ideal membranes and trade-off effect between permeability and selectivity is usually found.Compared with mesoporous membrane prepared from traditional materials,nanopores membranes fabricated from the polymerizable liquid crystalline molecules(LCM)have attracted increasing attention because nanopores can be generated easily from the magnetic and thermal field induced self-assembly.Therefore,it is very important for us to develop novel self-assemblying LCMs that can be used in the preparation of nanoporous membrane.In this thesis,a series of novel fan-shaped amphiphilic monomers were designed and synthesized.Intermediate product was synthesized from gallic acid methyl ester and 11-bromo-1-undecanol.It was then reacted with 5-PEG-2-nitrobenzyl alcohol that was synthesized from p-toluene sulfonyl terminated MPEG and 5-hydroxy-2-nitrobenzoic acid,to synthesize photoreactive molecules(TM1-1?TM1-2?TM1-3 and TM1-4)under the optimized conditions.The chemical structures of the product were analyzed by nuclear magnetic resonance.The thermodynamic properties of the materials with PEGs of different chain lengths were also studied.New liquid crystal molecules(TM2)was synthesized from methyl paraben,11-bromo-1-undecene and methyl gallate,and the chemical structure of the product was analyzed by nuclear magnetic resonance.The differential scanning calorimeter was used to study the liquid crystal behavior.The synthesized novels oligomers TM1-1,TM1-2,TM1-3 and TM1-4 were was determined that the complexed material showed distinct liquid crystal properties.The addition amount of lithium trifluoro-methanesulfonate displayed an abvious influence on the temperature ranges of the LC state of the complex.In addition,there were upper and lower limits for the amount of lithium trifluoromethanesulfonate added to oligomers.We believed that the suitable proportion of lithium trifluoromethanesulfonate to oligomers was in range from 1:1 to 1:2,in which they all showed obvious liquid crystalline properties.It was found that the transition temperature from glass state to liquid crystalline state of TM2 was greatly increased in comparasion with that of TM1.