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Abstract
Commercial applications of antimicrobial agents include textiles, food packaging and storage, the shoe industry, water purification, medical devices, and dental surgery equipment. There are ranges of antimicrobial agents with differing chemistries available commercially today and many more are being studied in academic laboratories. Quaternary polymeric compounds have proven to be very effective antimicrobial agents because of their unique structural properties. The scientific literature is replete with reports of surface modifications of different substrates by covalent attachment of these biocidal polymers. However, covalent surface attachment of biocidal polymers on common inert plastic materials such as polypropylene, polyethylene and polyvinyl chloride is very challenging with very few examples in the literature. In our study, we have successfully synthesized quaternary polyethylenimine based copolymers with a photoactive benzophenone pendant group that allows covalent attachment of copolymer on any surface with C-H bonds upon irradiation with mild UV light. The coating showed impressive antimicrobial activity against both Gram positive and Gram negative bacteria. A simple spray application technique was used to coat the substrates uniformly with copolymer to create permanent ultrathin biocidal coating. The other section of the work includes modification of natural fiber such as cotton with biocidal polymers. The main aim of the work was to design and optimize novel reactive copolymers, which can be applied on cellulosic textile materials using a simple application method such as the exhaustion. In this research, the goal was to incorporate hydroxy reactive groups on the backbone of quaternary polyethyleneimine (PEI) polymers. The covalent attachment of antimicrobial agent with fiber would improve its durability and avoid its release in the environment. To this end, three new copolymers were synthesized namely sulfated quaternary based PEI (SQ-PEI), monochlorotriazine based quaternary PEI (MCT-PEI) and dichlorotriazine based (DCT-PEI) which contain both fiber reactive vinyl sulfone, monochloro and dichlorotriazine side chains, respectively, and hydrophobic side chains (dodecane, C12). The polymeric antimicrobial agents were chosen because they have the advantages of being non-permeable through the skin, non-volatile, stable, efficient and selective. These polymers were tested for their antimicrobial properties and durability to accelerated laundering.