Semi-Crystalline, Three-Segmented Hybrid Gels with Multiple Shape-Memory Effect

Natural biological systems such as intervertebral disk, tendon, and ligament consist of regions with distinctly different mechanical properties, yet these regions intermesh with each other through an extremely tough interface. Here the authors present mechanically strong, three-segmented hybrid hydrogels comprising of soft and hard components in a fused body resembling the mechanical heterogeneity of biological materials. An easy UV-initiated bulk copolymerization method of stratified monomer solutions is used to synthesize three-segmented hybrid hydrogels. In this method, stratification of the monomer solutions is created by means of the differences in their densities. Thus, the polymerization reactions in the monomer mixtures as well as in the interface regions occur simultaneously resulting in the formation of multi-segmented hybrid hydrogels consisting of segments with different chemical and physical properties. Hydrophilic and hydrophobic monomer mixtures compositions of stratified solutions selected in this study lead to the formation of supramolecular, semi-crystalline three-segmented hybrid hydrogels with adjustable thermal and mechanical properties. They also exhibit thermally induced pseudo multiple shape-memory function originating from distinctly different melting temperatures of crystalline domains belonging to the gel components of hybrids.