Synthesis And Applications Of The Perfluoroalkyl-containing Antimicrobial Compounds

As the ever-growing demand for healthy living, there is a keen interest in materials capable of killing harmful microorganisms. Textile materials are suitable media for growing microorganisms. In the last few decades, the prevention of microbial attack on textile and wearers of textile materials has become increasingly important to consumers and textile producers. So far, various antimicrobial agents have been applied to impart antimicrobial properties to textile. Among them, the quaternary ammonium salts are widely used in antimicrobial finishing of textile.However, the antimicrobial materials would not essentially mean ensured safety of us. For example, to protect patients and the surgical team from infectious blood and other body fluids, some medical materials should possess not only antimicrobial properties but also blood repellency properties. The same is in the case of battle suits. To provide the treated surface with a low critical surface tension, fluorochemicals are most abundantly used for their ability to lower the critical surface tension of the treated surface well below that of most 'fluid other than a fluorocarbon.In the light of the facts above mentioned, we first designed and synthesized a novel quaternary ammonium salt (PFDA), which contains both perfluoroalkyl and diallyl groups. PFDA was designed to be a multifunctional textile finishing agent capable of providing fabrics with barriers against microorganisms, water, oil, soil and blood. The synthesis of PFDA was outlined in Scheme 1. Consequently, the antimicrobial activities of compound PFDA were tested against Escherichia coli 8099 as a Gram-negative strain and Staphylococcus aureus ATCC 6538 as a Gram-positive strain. Both the minimum inhibitory concentration(MIC) values were 7.8 μ g/ml. Moreover, diallyl groups were innovatively introduced into the target molecular, which made itself a good monomer for polymerization. By emulsion copolymerization, we applied PFDA as one of monomers to give the copolymeric emulsion, which was used to treat the cotton fabrics by the pad-dry-cure method. The treated fabrics showed good antibacterial properties. The killing bacterial fates against E. coli 8099 and S. aureus ATCC 6538 were 99.9% and 92.4%, respectively. At the same time, the treated fabrics also showed good oil repellency but little waterproof property.To obtain more accessible application and durable effect, another novel quaternary ammonium salt (PFSC) was designed and synthesized. The 3-(trimethoxysilyl)propyl group introduced into the molecule can bind to many material surfaces. That improved the durability of the treated materials as well as its scope of applications. The synthesis of PFSC was outlined in Scheme 2. PFSC was applied as a surface modification agent to provide the treated cotton fabrics with the durable antimicrobial activity and low critical surface energy simultaneously. The treated fabrics showed a 97.3 % killing bacterial rate against S. aureus ATCC 6538. Even after 10 laundering cycles, the antimicrobial activities of treated specimens still remained at a high level, reaching at 95.6%. The treated specimen also showed the super-low critical surface energy γc=20± l mN/m, which is markedly lower than 42+2 mN/m of man-made blood.