Physically crosslinked polyvinyl alcohol-dextran blend xerogels: Morphology and thermal behavior

Physically crosslinked hydrogels composed of different amounts of dextran in PVA matrix were prepared by applying freeze-thaw cycles to their aqueous solutions. Morphology, thermal properties and FTIR spectra of the resulting blend xerogels were examined by SEM, DSC, TGA and FTIR spectroscopy. Blend xerogels containing 10% (w/w) dextran showed more compatibility/miscibility according to SEM and DSC results. The Tg of the xerogels did not show any significant changes with increased dextran content. Introducing dextran into the freeze-thawed PVA structure affected crystal size distribution of PVA; and hence thermal degradation behavior of the xerogels. An increase in dextran content resulted in broader crystal size distribution; better and still lower thermal stability in comparison to virgin PVA and freeze-thawed PVA, respectively.