Antibacterial chitosan bioplastics with enhanced water stability via electro-assembly followed by direct thermal processing.

Current commercial bioplastics often suffer from inherent brittleness, poor water resistance, and a lack of intrinsic antibacterial activity, which severely restricts their application in active food packaging. To address these challenges, this study presents a robust sodium dodecyl sulfate (SDS)-reinforced chitosan (CS) bioplastic fabricated via a facile electro-assembly strategy followed by hot pressing. By leveraging the strong electrostatic interactions between anionic SDS and cationic CS, a densely packed molecular network was constructed. The optimized SDS-CS bioplastic overcomes the limitations of traditional casting methods, exhibiting exceptional toughness (41.3 MJ/m3) and high tensile strength (30.1 MPa). Unlike pure CS film, the composite demonstrates enhanced water stability, exhibiting a reduced water uptake rate (50.5%) and maintaining its mechanical integrity even after 30 days of immersion. Furthermore, the material possesses thermal recyclability and soil biodegradability (90% within 60 days). Crucially, the incorporation of SDS endows the bioplastic with sustained broad-spectrum antibacterial efficacy, achieving an antibacterial rate of 100% against S. aureus and 95.3% against E. coli over 96 h. This work provides a novel paradigm for developing bio-based, high-performance, and processable alternatives to petroleum-based plastics.