Polymer nanocomposites containing metal nanoparticles can be prepared by different methods: mechanical mixing of a polymer with metal nanoparticles; in situ polymerization of a monomer in the presence of metal nanoparticles; or in situ reduction of metal salts or complexes in a polymer [8,9] . These polymer nanocomposites have attracted a great deal of attention due to their unique properties and applications [10,11] . The literature describes many methods to prepare ultrafine silver powders [12][13][14][15] including the formation of Ag nanoparticles attached to bacterial cellulose [2,3] . In this work, we developed an easy method to produce composites with homogeneous size distribution of silver nanoparticles. This structure provides a robust, highlyporous and self-sustaining structure with large surface area, which is essential to facilitate incorporation of the silver ions in the metallization process to give a high silver loading content. Furthermore, the in situ direct metallization method was adopted to obtain a high loading content and strong bonding force of silver nanoparticles on the BC surface, thereby avoiding the Ag + contamination problem. The combination of the antibacterial efficacy of the silver nanoparticles and the biodegradability of the BC fibers in the composite fibers can make them practical for use as antimicrobial membranes in medical applications. Experimental MaterialsThe bacterial cellulose (BC) membranes were supplied by Fibrocel -Produtos Biotecnológicos Ltda. (Ibiporã, Brazil). Polyvinylpyrrolidone (PVP, MW = 29,000), gelatin,

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Abstract:We report the development of copolymers based on 2-vinylpyridine with different porosity degrees. The copolymers were quaternized with methyl iodide and acrylonitrile to introduce quaternary ammonium groups on pyridine units. To prepare charge transfer complexes, the unmodified copolymers and their derivatives quaternized were impregnated with iodine. The antibacterial properties of all the polymers were evaluated ranging from of the Escherichia coli strain. The unmodified copolymers did not have antibacterial activity against E.Coli suspensions. The quaternization with methyl iodine and acrylonitrile increased the biocidal performance of these copolymers, but only the copolymer with the lowest porosity modified with methyl iodine showed significant bactericidal action for all E. Coli concentrations. The 2-vinylpiridine copolymers quaternized and impregnated with iodine had higher antibacterial activity than the impregnated ones. The charge transfer complexes derived from the copolymer with the lowest porosity and highest swelling capacity in water had the best bactericidal performance.

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Microesferas poliméricas magnéticas à base de estireno (STY), divinilbenzeno (DVB), acetato de vinila (VAc) e ferro foram preparadas via polimerização em suspensão e semi-suspensão. Foram estudadas as influências da concentração de VAc adicionado na polimerização e da presença de ferro sobre as características das partículas poliméricas. Estas foram caracterizadas por espectroscopia vibracional na região do infravermelho por transformada de Fourier (FT-IR), análise termogravimétrica (TGA/DTGA), microscopia óptica por reflexão (MO), microscopia eletrônica de varredura (SEM) e magnetometria de amostra vibrante (VSM). Foram obtidas com sucesso microesferas poliméricas com propriedades magnéticas à base de estireno, divinilbenzeno e acetato de vinila. Estes materiais apresentaram bom controle morfológico esférico e partículas de ferro aglomeradas por toda a superfície da microesfera. O maior rendimento de microesferas magnéticas foi encontrado na faixa de 288 μm. Apresentaram também boas propriedades magnéticas (22,62 a 73,75 emu.g-1) com comportamento próximo de materiais superparamagnéticos e boa estabilidade térmica (444 °C).