High-strength and amphiphilic epoxidized soybean oil-modified poly(vinyl alcohol) hydrogels

Poly(vinyl alcohol) (PVA) hydrogels are widely used as biomimetic cartilage materials for its good biocompatibility and shock absorbing ability. However, the application of pure PVA hydrogel prepared through freezing–thawing method is limited by its disadvantages such as high flexibility and low mechanical strength. To solve these barriers, a biobased monomer, i.e., epoxidized soybean oil (ESO), was used to modify PVA to formulate a series of ESO cross-linked PVA (PVA-ESO) hydrogels. Infrared spectroscopy (FT-IR), X-ray diffraction and thermogravimetric analyses were used to confirm the formation of PVA-ESO copolymer. Scanning electron microscope revealed that the formed PVA-ESO hydrogels presented a distinct porous structure, while no obvious pores were observed on pure PVA hydrogel. The tensile strength of PVA-ESO hydrogels increased up to 2.4 times when compared to that of pure PVA hydrogel. Dynamic mechanical analysis indicated that the elastic properties of PVA-ESO hydrogels are better than that of pure PVA hydrogel, which are similar to that of natural cartilage. In summary, the modification of PVA with ESO can improve the thermal stability and mechanical properties of the hydrogels due to the improved cross-linking degree and the formed hydrophobic association.