Dual-Crosslinked Mechanically Strong Hydrogel Based on Poly(aspartic acid) via Cryogelation and Metal-Coordination

Many efforts have been made to develop highly strong and tough hydrogels by new approaches including double network (DN) hydrogel, nanocomposite hydrogel, nanostructured hydrogel, etc. In this study, macroporous monolithe gel based on chemically crosslinked poly(aspartic acid) (PASP) was prepared via cryogelation in DMSO and the following hydrolysis reaction under pH9 buffer. The resulting water-swollen gel was treated in next step with metal cation (Fe+3, Ca+2 or Zn+2) in aqueous solution to provide gel possessing ionic-crosslink between carboxylic acid and metal ions in addition to covalent network. The final dual-crosslinked PASP cryogel exhibited highly improved gel strength & toughness varying on the different metal species. The mechanical properties were investigated by both compression and tensile test to compare different cryogels with conventional PASP hydrogel. FTIR and SEM were used to elucidate the chemical structure and macroporous morphology of gel.