Development of novel bioactive waterborne polyurethanes: Effect of polyurethane chemical structure on its properties

In this work, a family of bioactive waterborne polyurethanes (WPUs), based on glycerol ethoxylate (GE), hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI), with specific bioactivity on their chemical structures constituted by the amino acids: L-tyrosine (T), L-histidine (H) or L-glutamic acid (Glut), using a mass ratio of each component of 56/29/15%, respectively, was synthesized by a condensation reaction at 80 ºC for 3 h. In the GPC analysis, the P(HDI-T) shows the highest average molecular weight (Mn) (20,264 g mol⁻¹), with a rod-like morphology, with a melting point of 240 ºC and with high resistance to endothermic degradation. IPDI-based WPUs exhibit a rough and amorphous structure, with a glass transition temperature around 120 ºC, regardless of the chemical structure of the amino acid present in their polymeric skeleton. The P(HDI-T) WPU it has the largest particle size. The in vitro biological evaluation reveals that the synthesized WPUs demonstrate to be non-hemolytic materials, benefiting the proliferation of important cells in the healing process such as monocytes and fibroblasts, and that they have antibacterial properties; evidencing that P(HDI-H) and P(IPDI-Glut) allow a 100% in vitro wound closure at 15 days. These novel bioactive synthetic polymers could be useful for the design of smart biomaterials as hydrogels made up of proteins using them as chemical crosslinker, taking advantage of the reactivity of the isocyanate groups.