Synthesis Of Multifunctional Superhydrophobic Antibacterial Materials And Studies On Their Surface Properties

Microorganisms,such as bacteria,are prone to form biofilm on the surfaces of materials,which poses severe threats to people’s lives,health,and industrial manufacture.With the fast development of global economy,plenty of environmental problems emerged.Particularly,maritime oil leakages and oily wastewater have become a worldwide problem demanding prompt solution.Recent researches have provided new insight into antibacterial performance and oil/water separation property of superwetting surfaces,including superhydrophobic/super-oleophilic and superhydrophilic/underwater superoleophobic surfaces.However,the antibacterial activity of most reported superhydrophobic surfaces was short-term,and could have some effects on environment.Besides,materials applied to oil/water separation are easily polluted by oil and microorganisms,causing the lower separation efficiency.Therefore,fabrication of multifunctional materials with long lasting antibacterial,ecofriendly,and stimuli-responsive properties is of great importance.In this study,quaternary ammonium salt(QAS)functionalized fluorinated copolymers tethered hydroxyl groups were synthesized by free radical polymerization.And then novel liquid-repellent and antibacterial nanocomposite coatings were prepared via cross-linking the fluorinated copolymer and poly(ureaformaldehyde)nanoparticles(PUF NPs)containing active methylol groups with hexamethylene diisocyanate(HMDI).The surface morphologies were studied by SEM,AFM measurements,and proved that introduction of PUF NPs increased roughness and formed micro/nano dual structure.Wettability of obtained coatings influenced by chemical compositions was further discussed by XPS and contact angle measurements,and it exhibited that surface contents of F and N+ were the two main factors affecting wettability.The prepared coatings owned excellent self-cleaning and liquid-repellent properties,and could be applied to various substrates.Moreover,the coating could maintain its superhydrophobicity even after 16 abrasion cycles and 20 cycles of cross-cut tape test.Antibacterial tests showed N+ content would affect antibacterial efficiency.The coating with 0.11%N+ surface concentration had a bactericidal rate of over 82%even 100%against E.coli and S.aureus.In order to obtain responsive smart materials,N,N-dimethylamino ethyl methacrylate(DMAEMA)was introduced into QAS functionalized fluorinated copolymer,and synthesized pH-responsive polymer.The smart antibacterial superhydrophobic cotton fabric was prepared by crosslink reaction of the responsive polymer,PUF NPs,and HMDI.The surface morphologies and chemical compositions of prepared cotton fabric treated by different pH solutions were measured by SEM,XPS,which displayed micro/nano hierarchical structure on surface.And it is not surface morphology but surface concentration of N+ that can be affected by pH solutions.The N+ content got distinctly increased after treatment by acid solutions.The pH-responsivity of coated cotton fabrics was investigated by water contact angle measurements,showing that only treatment by acid sulotions could change wetting behavior of coated fabric,and that the response time decreased with decreasing pH.Besides,the coated cotton fabric retained superb self-cleaning performance after contamination by oil,and held high bactericidal rate(more than 80%)after treatment by different pH solutions.Importantly,responsive coated cotton fabric achieved wettability transformation from superhydrophobicity/superoleophilicity to super-hydrophilicity/underwater superoleophobicity,thus selective separation or absorption of oil phase and water phase from oil/water mixture.