Synthesis and properties of temperature-sensitive and chemically crosslinkable poly(ether-urethane) hydrogel

Temperature-responsive and crosslinkable poly(ether-urethane)s (PEUs), which may be useful for tissue adhesives, are prepared through the polymerization of poly(ethylene glycol)s (PEG), mono-p-methoxybenzylidene-pentaerythritol and hexamethylene diisocyanate, the hydrolysis of acetals in PEUs and the grafting of methacrylate (MA) to PEUs. After gelating the PEU solution in a specific temperature range via a rapid reversible temperature response, the physical hydrogel is further self-cross-linked or cross-linked with PEG diacrylate (PEGDA) by photocuring. These PEU-MA gels are characterized by Fourier transform infrared spectra (FTIR), nuclear magnetic resonance (NMR) and size exclusion chromatography (SEC). The sol–gel phase transitions through temperature response and chemical crosslinking are investigated by rheology testing. It is found that the swelling ratio, degradation, adhesive strength and mechanical properties of the PEU-MA gels are affected by the ratio of hydrophilic and hydrophobic segments in PEU and the grafting ratios of MA in PEU-MA gels. The adhesive strengths on tissues with PEU-MA are stronger than those on glass and PBT. The adhesion of PEU-MA on artificial dura mater can be maintained for over one month, even when immersed in water. The good biocompatibility of the PEU-MA gels is demonstrated via cytotoxicity evaluation. As a result, these PEU-MA gels are promising candidates as tissue adhesives and drug-loading materials for soft tissue filling and regeneration.