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Synthesis And Antibacterial Activities Of Novel Polymeric Quaternary Ammonium Salts And Their Composites

Posted on:2013-01-17Degree:MasterType:Thesis
Country:ChinaCandidate:H D WangFull Text:PDF
GTID:2231330374957219Subject:Chemistry
Abstract/Summary:PDF Full Text Request
Antibacterial modification of surfaces to prevent growth of detrimentalmicroorganisms has great significance for controlling the spread of germsand protecting materials free from microbial corrosion. Therefore, theresearch on antibacterial agents and antibacterial functional materials hasalready aroused widespread concern. Quaternary ammonium salts receivemuch more popular acclaim because of their low toxicity, broadantibacterial spectrum, low cost and other fine features. At present,quaternary ammonium salts as antibacterial agents have been developed tothe sixth generation, polymeric quaternary ammonium salts. They showhigher antibacterial activity due to their higher charge density compared tosmall molecular compounds. However, with the enhancement of microbialresistance, the development of antibacterial agents possessing newstructures and superior antibacterial activities has gradually become aresearch hotspot.Based on the previous research, starting from the development of polymeric quaternary ammonium salts point of view, poly(vinyl alcohol)grafted with epoxypropyl quaternary ammonium salts were prepared in thisthesis. Their antibacterial test showed that grafted poly(vinyl alcohol) had acertain degree of disinfection potential. In order to exploit novelantibacterial agents with more excellent performance, silver bromidenanoparticles/polymers composites were prepared with a simple method ofon-site precipitation. These organic-inorganic composites have theoutstangding antibacterial activity due to the synergy of different types ofantibacterial agents. Detailed research contents are as follows:1. Preparation of poly(vinyl alcohol) grafted with epoxypropylquaternary ammonium salts: firstly, we synthesized N-epoxypropyl-N-dodecyl-N,N-dimethyl ammonium chloride. Then epoxy groups reactedwith hydroxyl of poly(vinyl alcohol) to form ether in alkali condition,consequently, antibacterial functional modified poly(vinyl alcohol) wereobtained. Furthermore, the optimal molar ratio of poly(vinyl alcohol) andN-epoxypropyl-N-dodecyl-N,N-dimethyl ammonium chloride wasdetermined. The result showed that the grafting degree achieved themaximum when the molar ratio was6:1. The modified poly(vinyl alcohol)were characterized by attenuated total reflection infared spectrometry(ATR-IR), scanning electron microscope (SEM), elemental analysis (EA)and thermogravimetric analysis (TGA).2. Synthesis of silver bromide nanoparticles/polymers composites: firstly, we synthesized alkylation of N,N-dimethylaminoethyl acrylate--2-imidazol1ylethyl acrylate diblock copolymers used as matrix for dopingsilver nanoparticles by the free radical copolymerization. Monomers anddiblock copolymers were characterizated by nuclear magnetic resonancespectrum (1H-NMR,13C-NMR). Silver bromide nanoparticles formed incopolymesrs with on-site precipitation method. Then organic-inorganicantibacterial composites were prepared. The resulting silver bromidenanoparticles were stabilized by the nitrogen atoms of imdazoles and stericeffect of polymers, thus were not subject to conglomerate or leak from thematrix. Then nanoparticles size and dispersion of silver bromide werecharacterized by XRD, TEM and EDS.3. Antibacterial testing: the bactericidal activities of grafted poly(vinylalcohol) and composites were evaluated by determing MBC values andinhibitory zone diameters. It was showed that the MBC values of graftedpoly(vinyl alcohol) and composites were25μg mL-1and0.125μg mL-1respectively.
Keywords/Search Tags:Poly(vinyl alcohol), Etherification, Polymeric quaternaryammonium salts, Silver bromide nanoparticles, Organic-inorganiccomposite, Antibacterial agents
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