Synthesis, characterization and biodegradation studies of poly(ester-urethane)s

A series of aliphatic poly(ester-urethane)s (PEUs) with different NCO/OH ratio were synthesized by a two-step bulk polymerization process from aliphatic poly(neopentyl-succinate) (PNSu), 4,4'-dicyclohexylmethane diisocyanate and 1,3-propanediol as a chain extender in the presence of dibutyltindilaurate as a catalyst. PNSu was prepared by the transesterification polycondensation from diethyl succinate and neopentyl glycol in the presence of titanium isopropoxide as a catalyst. The effect of the NCO/OH ratio on the structural, physical and thermal properties of PEUs was studied by Fourier transform infrared spectroscopy, X-ray diffraction, proton nuclear magnetic resonance, gel permeation chromatography, density measurement, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetric analysis and optical microscopy. The density (rho) and number-average molecular weight (M-n) of PEUs are found to be in the range of 1.175-1.180 g/cm(3) and 55 137-56 947 g/mol, respectively. The biodegradability of the PEUs film was investigated by hydrolytic (in 3% sodium hydroxide solution) and enzymatic degradation (Aspergilus niger lipase in phosphate buffer solution pH = 7.2) at 37 degrees C. PEUs film shows a slower degradation rate in A. niger lipase compared with the hydrolytic process.