On the intermolecular crosslinking of PVA chains in an aqueous solution by γ-ray irradiation

Abstract We studied how the polymer chains of poly(vinyl alcohol)(PVA) are crosslinked in its O 2 -free aqueous solution by γ -rays. The static–dynamic laser light scattering method was employed for determining the molecular weight ( M w ), hydrodynamic radius ( R h ) and radius of gyration ( R g ) for the original PVA ( M w =1.0×10 5 ) and its radiation products. The γ -ray irradiation from Co 60 to the PVA solutions with different concentrations was performed at different dose levels. It was found that both molar mass and size (i.e., R g and R h ) of the radiation products increased with a dose increase. The magnitude of these increases was enhanced by decreasing the polymer concentration ( C p ). In particular, at C p C p using the dose curves of M w . It became apparent that, regardless of C p , the intermolecular crosslinking reactions were dominant in the initial stage of irradiation. The radiation yield of intermolecular crosslinking was found to increase linearly when increasing C p , and at C p > the overlap concentration it asymptotically approached a limiting value estimated from the dimerization of pentane-2,4-diol as a model compound of PVA.