Stereocomplex mediated gelation of PEG-(PLA)(2) and PEG-(PLA)(8) block copolymers
Stereocomplex mediated hydrogels have been prepared by mixing solutions of polymers of opposite chirality of either PEG-(PLA)(2) triblock copolymers or PEG-(PLA)(8) star block copolymers. The critical gel concentrations of the mixed enantiorner solutions were considerably lower compared to polymer solutions containing only the single enantiomer. Moreover, gel-sol transition temperatures were increased and gel regions were expanded due to stereocomplexation. Rheology measurements showed that stereocomplexed hydrogels based on PEG-(PLA)(8) have higher storage moduli compared to those based on PEG-(PLA)(2). Stereocomplexed hydrogels prepared from 13 wt% PEG-(PLA)(2) solutions in PBS showed a storage modulus of 0.9 kPa at 37 degrees C, while at similar conditions stereocomplexed hydrogels of PEG-(PLA)(8) showed a storage modulus of 1.9 kPa at 10 wt%.