Preparation And Properties Of Organic Gels Formed By Side Chain Liquid Crystalline Polymer

Organic gels have attracted much interest due to their potential applications as self-assembling materials such as drug release,artificial intelligence,molecular devices,smart materials,environmental response materials and so on.In recent years,a large number of studies have been done on low molar-mass organic gelator.However,there are few reports on side-chain liquid crystal polymers as organogelators.As organogelators,the side-chain liquid crystalline polymers have many advantages such as simple preparation,low cost,controllability and excellent thermal stability.In this paper,a series of side chain liquid crystalline polymers were designed and synthesized as organogelators,and prepared a series of high-performance organic gels by heating cooling method.The relationship between gel property and gelators structure of side chain liquid crystalline polymers is studied in detail.The main work of this paper included several aspects:1.A series of side chain liquid crystal monomers named co-(4’-methacryloyloxy biphenyl-4-oxy)hexyl methacrylatel(M6BiCm,m is the length of alkoxy tails,m = 1,2,4,6,8,10,12,14,16,18)were designed and synthesized.A series of side chain liquid crystal polymers(SCLCPs)named poly[ω-(4’-n-alkyl oxybiphenyl-4-oxy)hexyl methacrylatels(PM6BiCm,m is the length of alkoxy tails,m = 1,2,4,6,8,10,12,14,16 and 18)were synthesized via free radical polymerization.The novel gelators were prepared by introducing M6BiCm/PM6BiCm into organic solvents.It found that the M6BiCm(m = 1,2,4,6,8,10,12)showed weak ability to gelate organic solvents,while M6BiCm(m = 14,16,18)exhibited excellent ability to gelate organic solvents.The PM6BiCm(m = 1,2,4)were insoluble in most organic solvents,while PM6BiCm(m = 6,8)exhibited excellent ability to gelate individual organic solvents.PM6BiCm(m = 10,12,14,16,18)showed excellent ability to gelate most organic solvents.It is found that the monomers formed the physical crosslinking point through the crystallization of alkoxy tail chain and self assemble into three dimensional network structures to form gel.Therefore,the gelation ability of the monomer and the thermal stability of the gel increased with the increase of alkoxy tail chain.Polymers are self assembled to form a network structure through the non-covalent interaction of side chains,the solvent molecules are adsorbed on the network structure through the tail chain.Therefore,the gelation ability of SCLCPs will increase with the increase of alkoxy tail chains.However,the increase of alkoxy tail chain will lead to the increase of the compatibility of the SCLCPs in the organic solvent,so the thermal stability of the gel decreases.2,A series of side-chain liquid crystal monomers named 4,4’-alkyloxybiphenyl methacrylate(MBiCm,m is the length of alkoxy tails,m= 1,2,4,6,8,10,12,14,16,18)were designed and synthesized.A series of side-chain liquid crystal polymers(SCLCPs)were named poly(4,4’-alkyloxybiphenyl methacrylate)(PMBiCm,m is the length of alkoxy tails,m = 1,2,4,6,8,10,12,14,16 and 18)were synthesized via free radical polymerization.The novel organogels were prepared by introducing MBiCm/PMBiCm into organic solvents.It found that,the MBiCm(m = 1,2,4,6,8,)showed weak ability to gelate organic solvents,while MBiCm(m = 10,12,14,16,18)exhibited excellent ability to gelate organic solvents.The PMBiCm(m = 15 2,4,6,8)were insoluble in most organic solvents,while PMBiCm(m=10,12,14,16,18)exhibited excellent ability to gelate most organic solvents.It was found that the gelation capacity of both monomers and polymers increased with the growth of alkoxy tail chains.The thermal stability of monomer gel was increases with the increase of alkoxyl tail chain length,while the thermal stability of polymer gel decreases with the increase of alkoxyl tail chain length,the reason is consistent with the second chapter.Further comparing the gel formed by PM6BiCm,it was found that the gel prepared by PMBiCm had better thermal stability,indicating that the latter formed a more stable gel structure.3.A series of side-chain liquid crystal polymers(SCLCPs)named poly(4,4’-alkyloxybiphenyl acrylate)(PBiCm,m is the length of alkoxy tails,m = 14,16,18)were synthesized via free radical polymerization.The novel organogels were prepared by introducing PBiCm into organic solvents.It found that,PBiCm(m = 14,16,18)exhibited excellent geltion ability to polar organic solvents,such as benzene,toluene andchlorobenzene.The thermal stability of gels formed by PBiCm is much higher than that formed by PMBiCm.4.A series of side-chain liquid crystal polymers without flexible named poly(4,4’-alkyloxybiphenyl methacrylate)(PMBiC18)with different molecular weights(Mn)and low molecular weight distributions ha-ve been successfully synthesized via ATRP method.The novel organogels were prepared by introducing PMBiC18 into organic solvents.The results show that molecular weight has great influence on polymer gel ability.When the Mn<4×104 g mol-1,the geltion ability was weak,and its gel thermal stability was poor.With the increase of Mn,the geltion ability and thermal stability of gel increased.When the Mn>4×104 g mol-1,the geltion properties and thermal stability of gel become stable.