New approach to evaluate microphase separation in segmented polyurethanes containing carbonate macrodiol

The solid state properties of segmented polyurethanes (TPU) are determined to a great extent by their microphase-separated structure thus making them attractive for several technological applications. In addition to microphase separation, hydrogen bonding and partial crystallization of the soft segments often contribute to the thermoplastic elastomeric behavior of TPUs. In this work, we applied infrared spectroscopy to determine the degree of microphase separation and quantitative analysis of H-bonds formation between functional groups of hard and soft segments in poly(carbonate-urethane)s (PCUs) with a narrow weight ratio from 35 to 41 wt% of hard segments. Using the Gaussian deconvolution of infrared spectroscopy peaks we determined the degree of microphase separation in synthesized PCUs, indicating for the first time, the significant contribution of the H-bonds present in mixed phase of hard and soft segments. Moreover, high content of mixed phase and additional physical carbonyl groups interactions of carbonate macrodiol resulted in the highest elastic modulus for PCU containing only 41 wt% of hard segments. The results demonstrated that the newly introduced deconvolution formula and detailed analysis of infrared spectra are a precise tool in determining the degree of microphase separation in segmented polyurethanes even at narrow segments ratio.