Synthesis and characterization of poly(vinyl alcohol) carbonate

Poly(vinyl alcohol) (PVA) was reacted with dimethyl carbonate (DR IC) to prepare PVA carbonate (PVAC), which is considered to have three structures, cyclic carbonate (I), monocarbonate (II) and crosslinking carbonate (III). Though the reaction proceeded easily in dimethyl sulfoxide at 120 degrees C without any catalyst, the yield of the ethanol-insoluble part of the products was less than that with the reaction containing a catalyst such as tetrabutylammonium bromide (TBAB). TBAB concentration did not affect the rate of carbonic esterification but affected the yield of the ethanol-insoluble part. The rate of carbonic esterification increased with an increase in reaction temperature, and the activation energy of this reaction was 114 kJ mol(-1). Carbonic esterification under reduced pressure showed a larger degree of esterification than that of the reaction under atmospheric pressure. PVAC was soluble in water at a low degree of carbonic esterification (DC) but became insoluble as DC increased. The thermal property of PVA reduced by the carbonic esterification was improved as DC increased. (C) 2000 Society of Chemical Industry.