With high water content(～90 wt%) and significantly improved mechanical strength(～MPa),double network(DN) hydrogels have emerged as promising biomaterials with widespread applications in biomedicine.In recent years,DN hydrogels with extremely high mechanical strength have achieved great advance,and scientists have designed a series of natural and biomimetic DN hydrogels with novel functions including low friction,low wear,mechanical anisotropy and cell compatibility.These advances have also led to new design of biocompatible DN hydrogels for regeneration of tissues such as cartilage.In this paper,we reviewed the strategies of designing high-strength DN hydrogel and analyzed the factors that affect DN hydrogel properties.We also discussed the challenges and future development of the DN hydrogel in view of its potential as biomaterials for their biomedical applications.
Waterborne polyurethane(WBPU)with controlled biodegradability and biocompatibility was synthesized by using poly(ε-caprolactone)(PCL)as the polyglycol,isophorone diisocyanate(IPDI)as the isocyanate,2,2-bishydroxymethylbutyric acid(DMPA)as the chain extender and 1,4-butanediol(BDO)as the hard-segment regulating agent.We found that BDO content significantlyinfluencedmechanicalproperties,degradable performances and cyto-biocompatibility of PCL-WBPUs.Increasing the BDO content in PCL-WBPU enhanced its tensile strength and decreases strain.Enzymolysis and hydrolysis properties were also regulated by BDO content,but with different mechanisms.Cytobiocompatibility was evaluated with ATDC5 cells.The results show that the biodegradability of PCL-WBPU is significantly determined by BDO content,which exerts a serious influence on its polymer structure,leading to resultant degradable properties.
