Poly(acrylic acid) (PAA) is considered as a crosslinking polymer
for PVA because it has multiple carboxylic acid groups in its repeating
units that can react with the hydroxyl groups in PVA, as well as
desirable characteristics such as good water solubility (which, for
example, could be used as the solvent for the casting solution).9
The crosslinking reaction decreases the hydrophilic character of
PVA and produces water and non-toxic products as well.17 Several
researchers have reported the crosslinking of PVA with PAA
through heat treatment.9,13 – 16 With these methods, PAA can be
chemically crosslinked between hydroxyl groups of PVA and carboxyl
groups of PAA. The oxygen-barrier and thermal properties
of pure PVA would be expected to improve through change in the
crystalline structure and packing density of formation of PVA/PAA
blend films.