Synthesis and properties of high performance biobased liquid crystal copolyesters toward load-bearing bone repair application

Abstract

In order to acquire satisfactory load-bearing bone substitute, a series of high performance biobased liquid crystal copolyesters derived from 4-hydroxybenzoic acid (HBA), phloretic acid (HPPA), vanillic acid (VA) and lactic acid (LA) were designed and prepared 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 copolyesters showed relative low melting temperatures (176–229 °C) and controllable crystallinity (15.3–36.5%), due to the increased molecular chain mobility caused by LA units and the multi-component copolymerization effect. Broad temperature range of nematic liquid crystal phase, good thermal stability as well as shear shinning and viscous melt flow behavior were observed for the copolyesters, indicating they had excellent melt processing ability. As compared with polyetheretherketone (PEEK) materials, the copolyesters exhibited better mechanical properties and hydrophilicity, which of the tensile strength and water contact angle were in range of 95 to 175 MPa and 72.5 to 84.8°, respectively, ascribing to the combination effect of its liquid crystal nature and chemical structure. In addition, the cytotoxicity test showed the copolyesters have good biocompatibility. It is shown that the unique combination of potential biodegradability, excellent mechanical properties, hydrophilicity and biocompatibility of the copolyesters make them prospective and suitable for application in load-bearing bone repair area.