One-Shot Preparation of Thermoresponsive Comb Polyurethane Hydrogel for Both Excellent Toughness and Large Volume Switching

Thermoresponsive degradable polyurethane (PU) hydrogels are expected as the next-generation biomedical devices, although they have an important trade-off relationship between toughness and thermoresponsive properties. Tough and thermoresponsive comb PU hydrogels are prepared by one-shot poly-addition between hexamethylene diisocyanate, triethylene glycol tartrate ester, poly(ethylene glycol) 300 (PEG300), and glycerol. The swelling ratio change between 4 and 40 degrees C decreases as the proportion of PEG300 increases and is maintained at 600% switching within 30% PEG300. Moreover, the one-shot preparation of comb PU hydrogel with PEG300 improves toughness up to 100 times compared to the original comb PU hydrogel. Rheological analysis suggests that the bimodal toughening phenomenon for the proportion of PEG300 is due to the network structure and the hydrophobic aggregation domain. This simple toughening method using a heteronetwork based on the kinetic difference of step-growth PU is expected to apply to other chemical structures.

Automated summary

In this study, tough and thermoresponsive comb PU hydrogels were prepared through one-shot poly-addition using hexamethylene diisocyanate, triethylene glycol tartrate ester, PEG300, and glycerol. The swelling ratio of the hydrogels decreased as the proportion of PEG300 increased, with toughness improving up to 100 times compared to the original hydrogel. Rheological analysis indicated that the bimodal toughening phenomenon was attributed to the network structure and hydrophobic aggregation domain.