The effect of particle size and molecular structure of starch-based crosslinkers on self-healing behavior of hydrogel

Self-healing hydrogels crosslinked by dialdehyde polysaccharides have been extensively studied. The particle size and molecular structure of dialdehyde polysaccharides significantly affect the self-healing properties and mechanical properties of hydrogels; however, the mechanism remains poorly understood. In this study, dialdehyde starch based crosslinkers with different size and aldehyde group content were employed to form hydrogels with carboxymethyl chitosan. The results demonstrated that increasing the aldehyde content and using nanoparticles (DASNP) enhanced mechanical strength but diminished self-healing capacity due to the formation of dense crosslinking sites. In contrast, micron particles (DANCS) or linear structures (DASS) improved self-healing capacity by facilitating flexible chain mobility and reducing aldehyde content. Time-domain nuclear magnetic resonance and molecular-level analyses further elucidated the differences in the self-healing behavior by examining the mobility of water molecules and polymer chains. This study provides valuable insight into the relationships between particle size and molecular structure and self-healing behavior.