Durable superhydrophobic and antimicrobial cotton fabrics prepared by electrostatic assembly of polyhexamethylene biguanide and subsequent hydrophobization

Growing evidence shows that healthcare textiles act as reservoirs of pathogens responsible for healthcare-associated infections. Fabrics fortified with antimicrobial and superhydrophobic properties are slowly emerging as an ideal weapon to tackle these infections, because of their bactericidal and fluid-repellent functionalities. In this work, such dual functional fabrics were developed by depositing polyhexamethylene biguanide on cotton fabrics, followed by inclusion of an epoxy alkane/epoxy cross-linker. A layer-by-layer technique was employed for the incorporation of polyhexamethylene biguanide in place of the conventional single layer ionic (carboxylate anions of cellulose and cationic polyhexamethylene biguanide) interaction. The role of the epoxy cross-linker is paramount as it achieves cross-linking of polyhexamethylene biguanide chains and also ensures the anchoring of epoxyalkane to polyhexamethylene biguanide chains through amine-epoxy reaction. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the presence of polyhexamethylene biguanide and epoxyhexadecane on the fabric surfaces. The fabric surfaces exhibited high static water contact angles (>150 degrees) and lower water shedding angle (<20 degrees). The fabrics demonstrated impressive antimicrobial performance against Escherichia coli bacterial species. Importantly, in a separate protocol, the fabrics also decreased attachment of Escherichia coli cells by 70%, thus confirming their potential in the prevention of biofilm formation. Both the antimicrobial property and superhydrophobicity were retained after 50 equivalent home laundering cycles.