Synthesis and Properties of Polycaprolactone and Polycarbonate-based Polyurethanes

Polycaprolactone polyurethane (PCL-PU) has excellent mechanical properties, good biocompatibility and biodegradability, which is widely used in biomedical materials and other fields. However, the domestic production capacity of polycaprolactone diols is unable to meet the production demand of the polyester-based polyurethane industry. The search for alternatives with comparable properties to polycaprolactone-based polyurethanes is of great research importance. Therefore, in this study, three polycaprolactone (PCL-diol) and polycarbonate (1,4-butanediol) ester polyols (PC-diol) with different relative molecular masses were prepared using Lewis pair- catalyzed controlled ring-opening polymerization, respectively. The structures of the two polyester diols were characterized by nuclear magnetic resonance hydrogen spectrometry (H-1-NMR) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis (MALDI-TOF MS). PCL-PU and polycarbonate polyurethane (PC-PU) were synthesized by the reaction of two polyester diols with 2,4-toluene diisocyanate (TDI) and chain extender 1,4-butanediol (BDO), respectively. The thermal properties, crystalline behaviors, and mechanical properties of the two polyurethanes were further investigated in a comparative manner by thermogravimetric analysis, differential scanning calorimetry analysis, and stress/strain test. The results show that PC-PU has similar thermal stability and thermal decomposition process as PCL-PU, and the initial decomposition temperature of both polyurethanes is higher than 260 degree celsius, and both of them have two thermal decomposition stages. PCL-PU has a faster crystallization rate, while PC-PU has a slower crystallization rate. Compared to PCL-PU, PC-PU has higher elongation at break (>1200%) and breaking strength (>45 MPa). This paper provides a scientific basis and rationale for the creation of PC-PU with comparable properties of PCL-PU, and provides impetus for the development of the polyurethane industry. [GRAPHICS]