Elution of polymers from poly(vinyl alcohol) cast gels with different degrees of polymerization and hydrolysis

Poly(vinyl alcohol) (PVA) gels physically crosslinked by microcrystallites were prepared by a cast‐drying method using PVA powders with different degrees of polymerization (nDP) between 300 and 2400 and hydrolysis (rDH) between 79.5 and 98.5 mol %. Polymer elution of gels in a limited amount of water was investigated by measuring the total carbon in the outer water by a total organic carbon analyzer. As a result, polymer elution was detected for all gels, the total amount of which depended on both nDP and rDH. In the cases of lower nDP and higher rDH, the gel became opaque and cracks were observed on the surface during a simple swelling process. On the other hand, polymers dissolved without cracks in the cases of higher nDP and lower rDH. These results are discussed on the basis of the network microstructure of the dried states before and after the polymer elution. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012