Designing hydrolysis-resistant Ti/Zn bimetallic catalyst based on the coordination activation mechanism to synthesize high molecular weight poly (1,5-pentene terephthalate) (PPeT)

Abstract

The high molecular weight poly (1,5-pentene terephthalate) synthesis and its molecular weight distribution control are still challenging, and one of the critical problems is the lack of efficient catalysts. Based on the coordination activation mechanism, a heavy metal free, hydrolysis-resistant and 1,5-Pentanediol soluble Ti/Zn bimetallic catalyst has been synthesized and characterized. The Ti/Zn bimetallic active center increases electron-absorption effect in catalyst to promote the esterification process, and the diol-metal alkoxide structure increases the production of oligomer ligands, which can effectively improve transesterification efficiency. The optimal polycondensation reaction temperature for PPeT synthesized with Ti/Zn bimetallic catalyst can be reduced to 230 °C, with an average reaction rate of 90.33 g mol−1·min−1. The number average molecular weight of PPeT can be increased to 3.02 × 104 g mol−1, and the polymer dispersive index can be as low as 1.90. As the number average molecular weight increases, poly (1,5-pentene terephthalate) has a tensile strength of 29.80 MPa and an elongation at break of 16.39%. More importantly, Ti/Zn bimetallic catalyst retains excellent catalytic activity after treatment with boiling water and has significantly improved hydrolysis resistance and storage stability. Ti/Zn bimetallic catalyst can significantly increase the molecular weight and melt viscosity of poly (1,5-pentene terephthalate), giving it the potential for a wider range of applications in plastics and fiber fields.