Crosslinking of poly(vinyl alcohol) and poly(vinyl acetate) using poly(maleic anhydride-alt-2,4-dimethyl-1,3-pentadiene) as polyfunctional crosslinker and decrosslinking by ozone degradation

Crosslinking and decrosslinking reactions of poly(vinyl alcohol) (PVA) and poly(vinyl acetate) (PVAc) using an alternating copolymer of maleic anhydride and 2,4-dimethyl-1,3-pentadiene (PMAD) as the polyfunctional crosslinker and subsequent ozone degradation are reported. PVA and PVAc are heated at 200 degrees C for 0.5 to 3 h in the presence of 5 to 30 wt % of PMAD in the solid state to obtain the corresponding crosslinked polymers. The reactions of a hydroxy group of PVA and an acetate group of PVAc with an anhydride group of PMAD slowly proceed to give insoluble polymers with a loose crosslinking structure. Almost no change in the thermal decomposition temperatures and the IR spectra is observed during the crosslinking reactions. The crosslinked PVA produces hydrogels with a high swelling ratio of 500 to 1700%, which are readily degradable during a reaction with ozone in water at 0 degrees C. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44229.