A Review of Polymer Composites Containing Quaternary Ammonium Salts: Synthesis, Antimicrobial Mechanisms, and Applications

ABSTRACT

Polymer composites containing quaternary ammonium salts (QAS) are highly effective antimicrobial materials used in various applications due to their potent ability to disrupt microbial cell membranes, leading to cell death. QAS is particularly valued in healthcare, food packaging, textiles, and water treatment, where microbial contamination is a major concern. Integrability into polymers enables the development of materials that not only have durable, flexible properties but also long‐lasting antimicrobial effects. The synthesis of QAS‐polymer composites (QAS‐PCs) is typically achieved either by covalently bonding QAS to the polymer backbone or by non‐covalently bonding QAS into the polymer matrix. Covalent bonding, often achieved through copolymerization with QAS monomers, forms a strong attachment that prevents leaching, thereby ensuring prolonged antimicrobial activity. The review examines the role of structural parameters, such as alkyl chain length, molecular architecture, and QAS concentration, in determining antimicrobial efficacy and biocompatibility. The antimicrobial mechanisms are systematically described, emphasizing electrostatic interactions between cationic QAS groups and negatively charged microbial cell membranes, membrane disruption, leakage of intracellular constituents, dissipation of membrane potential, and subsequent cell death. Current and emerging applications of QAS‐PCs in healthcare, food packaging, water purification, and textiles are also summarized. Finally, the review discusses existing challenges and outlines future research directions to develop safer, more sustainable, and high‐performance antimicrobial polymer composites. This review provides valuable insights into the rational design and practical implementation of QAS‐PCs for next‐generation antimicrobial technologies.