Synthesis and properties of biodegradable polycaprolactone/polyurethanes using fluoro chain extenders

In this study, biodegradable fluorine-containing polyurethanes (PU/OFHD) were synthesized using 4,4'-diphenylmethane diisocyanate, polycaprolactone diol (PCL), and 2,2,3,3,4,4,5,5,-octafluoro-1,6-hexanediol (OFHD). PCL is a biodegradable soft segment, and OFHD is a fluoro chain extender. In addition, other polyurethanes (PU/HD) were synthesized using 4,4'-diphenylmethane diisocyanate, PCL, and another chain extender [i.e., 1,6-hexanediol (HD)] for comparison. Gel permeation chromatography analysis indicated that the molecular weight of PU/OFHD is greater than that of PU/HD. F-19 nuclear magnetic resonance analysis revealed that the OFHD chain extender was successfully incorporated into the backbone of PU. According to Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses, strong interactions between the C=O and CF2 groups in PU/OFHD exist. Based on thermal analysis, PU/OFHD exhibited an initial decomposition temperature that was 6.5-7.9 degrees C higher than that of PU/HD. Differential scanning calorimetry and dynamic mechanical analysis analyses indicated that both the glass transition (Tg) and dynamic Tg of PU/OFHD are higher than those of PU/HD. Mechanical property analysis demonstrated that the tensile strength of PU/OFHD is higher than that of PU/HD. Moreover, PU/OFHD exhibited better chemical resistance than PU/HD. The scanning electron microscope images indicated that both PU/HD and PU/OFHD exhibited higher hydrolytic degradation at a higher PCL content. However, PU/OFHD is less degradable than PU/HD. Copyright (c) 2015 John Wiley & Sons, Ltd.