SYNTHESIS OF GRAFT COPOLYMER BY COUPLING CONDENSATION THROUGH ACETALIZATION

A condensation coupling through acetalization is performed between hydroxyl groups on poly(vinyl alcohol) (PVA) and an aldehyde group attached to the chain end of poly(vinyl acetate) (PVAc) to produce PVA-VAc graft copolymers. The aldehyde-terminated PVAc is prepared by polymerization of VAc with monochloroacetaldehyde or monochloroacetaldehyde diethyl acetal as the chain transfer agent. The coupling reaction of PVAc with cross-linked porous beads of PVA, followed by extraction of ungrafted PVAc, permits us to estimate the fraction of PVAc carrying the terminal aldehyde group. The observed fractions range from 0.1 to 0.5. In addition to the heterogeneous grafting onto the cross-linked beads and a membrane, PVAc is grafted onto a linear PVA in dimethyl sulfoxide, which is a common solvent for both polymers. Based on the weights of the isolated graft copolymer and the two homopolymers, the number of branches in the graft copolymer is evaluated; for instance, 18 branches of PVAc with Pn of 53 are found to be coupled to the PVA backbone with Pn of 1340. © 1979, American Chemical Society. All rights reserved.