Reversible Crosslinking and Decrosslinking of Polymers Containing Alcohol Moiety Using an Acyclic Bifunctional Vicinal Triketone

In this article, we report reversible crosslinking and decrosslinking systems of commercially available alcoholic polymers, using a bifunctional vicinal triketone (bistriketone) as a crosslinking reagent. A small amount of the bistriketone (0.2 equiv of the tricarbonyl moiety relative to the OH group of the polymer) was added to a solution of poly(2-hydroxyethyl methacrylate) (PHEMA) in dimethyl sulfoxide (DMSO). After 4 days, the networked polymer was obtained as a yellow-colored gel in 97% yield. Conversely, the resulting gel could be decrosslinked by treatment with MeOH for 4 days to recover the original PHEMA in 94% yield as well as the bistriketone in 54% yield. The network formation and dissociation behaviors were investigated in detail by H-1 NMR and size exclusion chromatography experiments. Similarly to PHEMA, reversible crosslinking and decrosslinking of poly(vinyl alcohol) were achieved by addition of the bistriketone and by treatment of the resulting gel with H2O/DMSO (1/9, v/v), respectively. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 921-928