Preparation of high tough poly(vinyl alcohol) hydrogel by soaking in NaCl aqueous solution

High tough poly(vinyl alcohol) (PVA) hydrogels were prepared by repeated freezing/thawing processes and subsequently soaking in saturated NaCl aqueous solution. The PVA hydrogels were characterized via tensile testing, differential scanning calorimetry and scanning electron microscopy respectively. The results showed that during soaking in NaCl aqueous solution the PVA chain-entanglement network was formed and the water was included into the PVA chain-entanglement network. The tensile strength and elongation at break of PVA hydrogel firstly increased with the prolongation of immersing time and then decreased with the immersing time beyond 30 min. By this way the tensile strength and elongation at break of PVA hydrogel could reach up to 1.61 (±0.24) MPa and 631 (±80)%, respectively. This tough PVA hydrogel was prepared at the absence of chemical crosslinker and thus might be considered as a favourable candidate for tissue engineering applications.