Construction of Reversible Crosslinking－Decrosslinking System Consisting of a Polymer Bearing Vicinal Tricarbonyl Structure and Poly(ethylene glycol)s

― Effect of Concentration and Molecular Weight of Poly(ethylene glycol)s as Crosslinking Reagents ―

Abstract

In this article, we report a novel reversible crosslinking－decrosslinking system consisting of a polymer bearing vicinal tricarbonyl moieties in its side chain and poly(ethylene glycol)s (PEGs). A mixture of the tricarbonyl polymer and PEG (M_n＝600－20,000, 0.1－3.0 equiv of OH groups relative to the vicinal tricarbonyl moieties) in CH₂Cl₂ spontaneously turned into an orange-colored gel, in which a network structure was formed through hemiketal linkage. Conversely, the resulting networked polymer could be decrosslinked by treatment with water-containing solvent to recover the linear vicinal tricarbonyl polymer as its hydrate form in up to 96% yield. Following dehydration process by heating at 100 ℃ under reduced pressure regenerated the original vicinal tricarbonyl polymer.