Synthesis and properties of high performance aromatic thermotropic liquid crystal copolyesters based on naphthalene ring structure

In order to obtain thermotropic liquid crystal polymers (TLCP) with excellent comprehensive performance, naphthalene monomers (amount exceeding 50 mol%) of 6-hydroxy-2-naphthoic acid (HNA) and 2,6-naphthalene dicarboxylic acid (NDA) were used to prepare wholly aromatic TLCP with strong molecular interaction via “one-pot” melt polymerization method in this work. The structure and properties of the copolyesters were fully investigated by experimental measurements and molecular simulation. The simulation results indicated that the naphthalene TLCPs had less chain mobility and stronger molecular interactions, and resulted in a linear rigid chain conformation, endowing the copolyesters with superior properties. As compared with the control copolyester M without naphthalene units, the resulted copolyesters had higher glass transition and melting temperature, higher melt tension, better thermal stability and fiber mechanical property. Overall, the rigidity, molecular interaction and properties of the obtained copolyesters could be efficiently improved after incorporation of the naphthalene units, which is beneficial for its processing and application.