Utilization of freeze thaw process for polyvinyl alcohol/sodium alginate (PVA/SA) hydrogel composite

Polyvinyl alcohol/sodium alginate (PVA/SA) hydrogel was successfully prepared by freeze thaw process. Without crosslinking agent, hydrogel was formed by using 3, 5 and 7 consecutive cycles of freeze thaw. Hydrogel can be formed by hydrogen bonding formation between OH-group of sodium alginate and polyvinyl alcohol throughout network. Scanning electron microscope reported that microstructure of hydrogel was well packed. The interconnect porosity was also observed. Differential scanning calorimetry exhibited that two exothermic peaks at temperature of 110℃ and 225℃ were observed due to evaporation of water molecule and melting temperature of hydrogel, respectively. The swelling behavior was rapidly increased within initial stage and then it was dimensionally stable. With low sodium alginate content, tensile strength was slightly superior, whereas low in vitro degradation behavior was observed. It was remarkable to note that polyvinyl alcohol/sodium alginate (PVA/SA) hydrogel exhibited outstanding properties for being as a medical material.