Molecular insights into the mechanism between the structural and mechanical properties of glycol chitosan methacrylate hydrogels.

Glycol chitosan (GC), a derivative of chitosan with ethylene glycol branches, is favored in pharmaceuticals due to its nontoxicity and versatility. When modified with methacrylate, GC forms a photocrosslinking hydrogel, glycol chitosan methacrylate (GCMA), which is highly biocompatible and hydrophilic, making it suitable for drug delivery and tissue engineering applications. However, studies on its fundamental properties are limited. This research uses molecular dynamics simulations and experiments to explore how methacrylation affects GC's structural, mechanical, and molecular characteristics. Results show that methacrylation increases Young's modulus, making the material more brittle with shear-thinning and self-healing properties, consistent with an observed decrease in hydrogen bonding. Simulations reveal that reduced hydrogen bonds shorten the polymer's end-to-end distance, causing it to curl and enhancing its mechanical strength. Furthermore, the hydrophobic nature of the methacrylate group is indicated by reduced hydrogen bonds between molecular chains and water. This study deepens the understanding of GC and GCMA, highlighting the importance of hydrogen bonding, network density, and chemical interactions in determining the material's properties.