Segment-Selective Design of Zwitterionic Biodegradable Polyurethane with Tunable Service Lifetime

Biodegradable polymers often suffer from a trade-off between mechanical strength and degradability. In this study, zwitterionic biodegradable polyurethane (Z-TPU) was designed by introducing sulfobetaine groups through the reaction between tertiary amines and 1,3-propane sultone. The ionic interactions induced by zwitterions are expected to enhance microphase separation and mechanical properties. To investigate the effect of zwitterion location, zwitterionic groups were selectively introduced into either the soft or hard segment of polyurethane. Polycaprolactone-based soft segments were incorporated to provide hydrolytic biodegradability. In addition, a low-moisture-absorbing biodegradable TPU coating was applied to control water uptake and delay degradation during use. This study suggests a molecular design strategy for biodegradable polyurethane with both high durability and tunable degradation behavior.