Synthesis And Characterization Of Side-chain Liquid Crystalline Polymers With T-shaped Mesogens

Based on the concept of “unconventional shaped liquid crystalline polymers”, we designed and synthesized a series of side-on liquid crystalline polymer(SLCP) with T-shaped mesogens.These T-shaped SLCPs, in which the mesogens connect to the main chain directly without the flexible spacer, can form a columnar phase. But because of the unique T shape, the steric arrangement is harder, so their liquid crystalline phase is weak when the alkyl tail chain is short. And when the alkyl tail chain is elongating, the microphase separation facilitates the formation of liquid crystalline phase, with the phase translate from square columnar phase(Φs) to hexagonal columnar phase(Φh), at last to a oblate columnar phase(Φob). We argued the detail phase transition based on SAXS results. Also, we find that when the alkyl tail chain is very long, the polymer can dissolve in nonpolar solvent like n-octane. So we measured the solution self-assemble behavior in n-octane with different concentration. The result shows that these polymers can assemble into columnar phase in n-octane.And then we changed the “benzene-ether-benzene”(BEB) structure of the T-shaped skeleton into a “benzene-alkynyl-benzene”(BAB) group, which is more rigid, to investigate the effect of the rigid part to the phase behavior and the emission effect of BAB group. The result indicates that when the T-shaped skeleton becomes more rigid, the phase structure is worse with the same alkyl chain, and the translation betweenΦsto Φobcan also behaved by elongating the alkyl tail chain.Also, the BAB-based T-shaped polymers evidence an AIE effect.At last, based on the “Mult-Chain Model” in side-on LCPs, we also investigated the number of chains in one column in this system of T-shaped SLCPs. There’re 3 chains in the column of this system, indicating it’s coincident to the “Multi-chain Model” but not the “Single-Chain Model”.