The influence of mechanical stretching and freeze-thaw processing on the properties of polyvinyl alcohol hydrogels for drug delivery applications

Abstract

The study describes the development of physically cross-linked polyvinyl alcohol (PVA) hydrogels using uniaxial orientation via freeze-thawing (F/T). Although cryogels have shown significant improvements in long-term stability, high tensile strength, high elastic mechanical character and high degree of swelling [1,2], stretching hydrogels in between freeze-thawing cycles could change its properties and might be modulated for drug delivery systems. It has been proved that the stretched hydrogels are mechanically stronger and easier to handle than typical hydrogels of the same composition and dimensions [3]. In addition, the stretching process can induce a uniaxial polymer chain alignment while maintaining sufficient porosity and water content (>95%) [3]. Therefore, the hypothesis of this study is the stretched PVA/CAF hydrogel can highly improve the drug releasing rate and its tensile strength.