Cryo-hydrogel-rubbery elastomer

containing above 85% water was prepared by freezing aqueous solution of poly (vinyl alcohol) (PVA). Structure of cryo-PVA-hydrogel was studied by TEM. Experimental results showed that the cryo-hydrogel was a non-covalent bonded gel formed due to linking of polymer "clusters".Electron microscopy demonstrates the heterogeneous porous structure of the cryogel. It was found that the porous structure become more and more perfect with increasing the freezing time and polymer concentration.It is considered that phase separation plays an important role in gelation.The freezing is to encourage the phase separation and reinforce the mechanical strength.