While lower critical solution temperature (LCST)-type thermosensitive block copolymer hydrogels have been intensively studied for various applications, no thermoreversible injectable block copolymer hydrogels based on upper critical solution temperature (UCST)-type thermosensitive polymers have been reported. Here we present a class of thermoreversible physically crosslinked hydrogels from linear ABA triblock copolymers composed of a poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMMA) middle block and UCST-type thermosensitive poly(acrylamide-<i>co</i>-acrylonitrile) (P(AAm-<i>co</i>-AN) outer blocks. The triblock copolymers are synthesized by reversible addition-fragmentation chain transfer polymerization using a difunctional chain transfer agent. At appropriate block lengths and chemical compositions as well as sufficiently high polymer concentrations, the ABA triblock copolymers undergo reversible sol-gel transitions in water upon cooling, and the sol-gel transition temperature can be tuned by varying outer block length, AN molar content in the outer block, and polymer concentration. Dynamic light scattering study shows that the cooling-induced gelation is caused by the UCST behavior of the outer blocks of the ABA triblock copolymers. It is our belief that these UCST-type thermosensitive block copolymer hydrogels will have potential applications in many areas.

UCST-type thermosensitive linear ABA triblock copolymer hydrogels

254th National Meeting (2017)

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