Alkaline-Soluble Chitosan Quaternary Ammonium Polymer: Antibacterial Mechanism and Performance Applications

Natural rubber (NR) is a strategic biomaterial whose latex-based products are widely used in biomedical and hygienic applications. However, the inherent susceptibility of NR to microbial colonization limits its service life and poses safety concerns. To impart intrinsic antibacterial functionality, we designed a cationic-modified chitosan derivative (CS-GTA) by grafting quaternary ammonium groups onto the chitosan backbone via chemical bonding. This molecular tailoring significantly enhanced the solubility of chitosan under alkaline latex conditions. The resulting CS-GTA was introduced as a functional antibacterial filler into natural rubber latex, forming a stable and homogeneous NR/CS-GTA composite system. The modified latex retained favorable processability and curing characteristics. Using Dunlop foaming, casting methods and mechanical ball milling, we fabricated latex foam and thin-film materials, both of which exhibited remarkable inhibitory effects against Escherichia coli, Staphylococcus aureus, and Candida albicans, demonstrating broad-spectrum antibacterial performance. This study offers a sustainable and effective strategy for developing high-performance antibacterial natural rubber materials, with potential implications for advancing the value-added applications of NR-based products.