pH/Thermosensitive hydrogels formed at low pH by a PMMA-PAA-P2VP-PAA-PMMA pentablock terpolymer

A poly(methyl methacrylate)-block-poly(acrylic acid)-block-poly(2-vinyl pyridine)-block-poly (acrylic acid)-block-poly(methyl methacrylate) (PMMA-PAA-P2VP-PAA-PMMA), pentablock terpolymer has been synthesized by anionic polymerization with sequential addition of monomers and studied in aqueous media at low pH. The system exhibits combined properties and adopts the behavior of 'telechelic' polyelectrolytes and that of double hydrophilic polyampholytes. This complex behavior leads to the pentablock terpolymer forming a pH and temperature sensitive reversible hydrogel at very low polymer concentration.