Simple and versatile method for the one‐pot synthesis of segmented poly(urethane urea)s via in situ‐formed AB‐type macromonomers

Abstract

AbstractWe present a one‐pot method for the synthesis of poly(urethane urea)s (PUUs) with uniform (monodisperse) hard segments that eliminates tedious approaches to control the exothermic nature of isocyanate–amine reaction, is less sensitive to impurities and involves no isolation of intermediates. Reaction of two moles of hexamethylene diisocyanate with one mole of polycaprolactone of various molecular weights under optimum time and temperature led to NCO‐terminated polyurethane prepolymers. Addition of an equimolar quantity of benzoic acid and excess dimethylsulfoxide at ambient temperature produced quantitative yields of PUUs with high molecular weight. The structure of the PUUs was fully characterized using spectroscopic methods and a reasonable mechanism for the reaction sequences was determined via preparation and characterization of a model compound. Dynamic mechanical thermal analysis data confirmed the phase‐separated structure of the PUUs. Evaluation of stress‐strain curves revealed the wide‐ranging mechanical properties depending on soft‐segment molecular weight. Monitoring the remaining weight and molecular weight of polymers incubated in phosphate‐buffered saline showed hydrolytic degradability with rate depending on soft‐segment molecular weight. Also, a preliminary investigation of the interaction of L929 fibroblast cells with the prepared polymers confirmed no cytotoxicity and acceptable cytocompatibility for the PUUs. Copyright © 2010 Society of Chemical Industry