High-density polystyrene-grafted silver nanoparticles and their use in the preparation of nanocomposites with antibacterial properties.

The achievement of uniform nanoparticles distribution in polymer matrix is still a major challenge in the design and fabrication of polymer nanocomposites with desired properties. In this paper we propose a novel approach for the preparation of homogeneous polystyrene/silver nanocomposites utilizing Nitroxide Mediated Radical Polymerization (NMRP). In the first step of the developed procedure, the polystyrene grafted silver nanoparticles (Ag@PS) with well-defined core-shell structure and exceptionally high grafting density (from 2 chains/nm2 to 5.9 chains/nm2 ) have been synthesized through late injection of nitroxide-coated silver nanoparticles (N-AgNPs) into a TEMPOL mediated styrene polymerization system. Afterwards, the synthesized Ag@PS have been used for the preparation of nanocomposites (PS/Ag@PS) by mixing them with narrow-dispersity polystyrenes and thermoforming at 140°C. Due to the high flexibility of polymer chains attached to silver surface through nitroxide linker, free volume effect enables interpenetration of polystyrene molecules that provides excellent mutual miscibility of Ag@PS with polymer matrix. The synthesized nanohybrids (Ag@PS) and their nanocomposites (PS/Ag@PS) exhibit effective antibacterial activity with respect to pathogenic bacteria: Pseudomonas aeruginosa (Gram-negative representative) and Staphylococcus aureus (Gram-positive representative).