Biodegradable stimuli-responsive hydrogels based on amphiphilic polyaspartamides with tertiary amine pendent groups

Novel thermo- and pH-responsive hydrogels based on amphiphilic polyaspartamides possessing a lower critical solution temperature (LCST) and a volume-phase transition were prepared and characterized. The polyaspartamide derivatives were synthesized from polysuccinimide, which is the polycondensate of L-aspartic acid monomer, through successive ring-opening reactions using hydrophobic 2-diisopropylaminoethylamine and hydrophilic ethanolamine. The amphiphilic copolymer was then crosslinked with hexamethylene diisocyanate to afford the corresponding gel. The LCST of the copolymer in an aqueous solution was varied by changing both the graft composition and pH of the medium. The crosslinked gels showed stimuli-responsive behavior, with their degree of swelling and porous structure morphology changing with temperature and pH. In addition, hydrolytic degradation depending on the crosslinking density of the hydrogel was examined. (C) 2009 Society of Chemical Industry