Biodegradable poly(trimethylene carbonate-b-(L-lactide-ran-glycolide)) terpolymers with tailored molecular structure and advanced performance

The macroinitiator of poly(1,3-trimethylene carbonate) (PTMC) with number-average molecular weight (Mn>) of 9.6x10(3)gmol(-1) was synthesized by ring-opening polymerization at 120 degrees C. Then, the novel terpolymer P(TMC-b-(LLA-ran-GA)) consisting of PTMC homopolymer segment attached with various monomer molar ratios of L-lactide (LLA) and glycolide (GA) random copolymerization block was prepared with about 5.0x10(4)gmol(-1) by ring-opening polymerization in bulk at 140 degrees C. The tailored molecular structures of P(TMC-b-(LLA-ran-GA)) were characterized by H-1 nuclear magnetic resonance, C-13 NMR, FTIR, and gel permeation chromatography, and chain microstructure analysis was performed in detail with C-13 NMR spectroscopy. The effect of GA units on the thermal and crystallization behaviors, mechanical properties, as well as biodegradability of terpolymers was investigated by differential scanning calorimetry, wide-angle X-ray diffraction, stress-strain measurements, and in vitro tests in comparison with corresponding poly(trimethylene carbonate-block-L-lactide) copolymer P(TMC-b-LLA). The results show that amorphous PTMC segments have a significant effect on condensed state behavior of the terpolymers, and the incorporation of GA units strongly decreases the crystallinity and crystallization ability of LLA segment within terpolymers because of more random LLA-GA sequence and shorter average LLA block length. Meanwhile, the toughness of materials is greatly improved, and in vitro degradation is also accelerated. Peripheral vascular stents were 3D printed for the first time and met the requirements for application. The results show totally biodegradable terpolymers with unique molecular structure, and modifiable properties are promising new biomaterials with advanced performance for biomedical application.