Phenylboronate-diol crosslinked polymer gels with reversible sol-gel transition

Covalent dynamic gels based on reversible phenylboronic acid-diol ester bonds were prepared by crosslinking of N,N-dimethylacrylamide-4-((4-vinylbenzyloxy)carbonyl)phenylboronic acid copolymer, poly(VPB-co-DMA), and poly(2,2-bis(hydroxymethyl)butyl acrylate) (PHBA) in several organic solvents at ambient temperature. These gels formed rapidly and revealed typical properties of chemical gels. Analysis of the composition-property relationships of these polymer gels, specifically considering the effects of pH, molar ratio of HBA to VPB units, and gelator concentrations on dynamic rheological properties, were performed. Additionally, the polymer gels can be switched into their starting polymer solutions by adjusting pH of the system. The reversible sol-gel phase transition can be performed for several cycles in a similar way of supramolecular gel. Moreover, the gel revealed interesting self-healing property which occurred autonomously without any outside intervention. Employing this dynamic character, it is possible to regenerate the used gel, and thus has the potential to perform in a range of dynamic or bioresponsive applications. (C) 2011 Elsevier Ltd. All rights reserved.