Carboxymethyl chitosan/oxidized sodium alginate self-healing emulsion gels with enhanced physical stability

This study presents a general approach for fabricating polysaccharide-based self-healing emulsion gels with superior physical stability. The emulsion gels were synthesized by crosslinking carboxymethyl chitosan (CMC)-stabilized emulsions with oxidized sodium alginate (OSA). The self-healing properties of the gels were attributed to the formation of reversible imine bonds between the primary amino groups (-NH 2 ) of CMC and the aldehyde groups (-CHO) of OSA. Gelation occurred rapidly (20–60 s) upon mixing the CMC-stabilized emulsion with the OSA solution. Microstructural analysis revealed that the dispersed oil droplets were tightly encapsulated within an interconnected gel network. The compressive strength and rheological properties of the CMC-OSA emulsion gels were influenced by the mass ratio of CMC to OSA and the preparation parameters of OSA. Furthermore, the CMC-OSA emulsion gels demonstrated rapid self-healing at room temperature without external stimuli, along with excellent injectability. Owing to the 3D gel-like network structure and reversible interactions at the oil/water interface and within the continuous phase, the emulsion gels exhibited exceptional physical stability, including storage stability, freeze-thaw stability, pH and ionic stability, thermal stability, and centrifugal stability. This study provides a promising strategy for developing injectable self-healing emulsion gels with tunable mechanical properties and enhanced physical stability for multifunctional applications.