Functional modification of poly(vinyl alcohol) by copolymerization: IV. Self-crosslinkable poly(vinyl alcohol)s

An investigation has been made on the copolymerization of vinyl acetate with N-(methoxymethyl)-acrylamide, N-(n-butoxymethyl)-acrylamide or N-methylol-acrylamide, and or the alcoholysis of copolymers and crosslinking properties of the resulting modified poly(vinyl alcohol)s (PVALs). The former two comonomers, N-(alkoxymethyl)-acrylamides, have been found useful for producing self-crosslinkable PVALs where timing of crosslinking is controllable: no crosslinks are included in the powder or in aqueous solution, and crosslinked materials having high water-resistance can be produced in the dry state with the aid of ammonium chloride. The following crosslinking reaction can be assumed: From a modified PVAL containing 1.0 mol% of N-(n-butoxymethyl)-acrylamide units, a crosslinked film showing high resistance to boiling water, 0.8% of the sol fraction and 2.4% (w/w) of the swelling degree, has been obtained. Modification with N-(methoxymethyl)-acrylamide also shows a similar performance. In contrast, N-methylolacrylamide cannot be used for this purpose because crosslinking occurs in alcoholysis. The monomer reactivity ratios for the copolymerization of N-(n-butoxymethyl)-acrylamide (monomer-1) and vinyl acetate (monomer-2) have been determined as r1 = 8 and r2 = 0.095.