Thermally-responsive biopolyurethanes from a biobased diisocyanate

Abstract

In this work, segmented biopolyurethanes with thermally-activated shape-memory properties were synthesized and characterized. All the employed starting materials were derived from renewable sources. The macrodiol, which forms the hard segment, was derived from castor oil, while the soft segment was composed of a diisocyanate from the amino acid lysine, as well as a chain extender from corn sugar. The effect of component molar ratios and switching temperature on the shape-memory behavior was analyzed. Thermal analysis of the biopolyurethanes shows a phase separated structure. Programming at different temperatures resulted in shape-memory effects, in which shape fixation and recovery could be attributed to different phases of the physical networks. Increasing the switching temperature, shape fixity values improve, however, it has no significant effect on shape recovery values. In addition, preliminary in vitro cytotoxicity evaluation shows that the synthesized fully biobased biopolyurethane has a non-toxic behavior, showing its potential to be used in biomedical applications.