Synthesis of bactericidal polymer coatings by sequential plasma-induced polymerization of 4-vinyl pyridine and gas-phase quaternization of poly-4-vinyl pyridine
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Plasma-based technology is an alternative to produce universal polymer coatings with the appropriate requirements of robustness and stability for antibacterial applications. Here, we proposed a sequential two-step alternative to synthesize antibacterial polymer coatings. A non-isothermal plasma reactor, operated at atmospheric pressure (Patm) and room temperature (Troom), was used to induce free radical polymerization of 4-vinyl pyridine (4VP) on high-density polyethylene (PE). In a subsequent step, the poly-4VP (P4VP) films were treated with a bromoethane/He gas stream to produce quaternized P4VP (P4VPQ) films. Chemical structure of polymer films was validated by infrared and UV–visible spectroscopy, and morphology was evaluated by optical and atomic force microscopy; scanning electron microscopy was used to determine films thickness, which was then used to estimate the surface charge density. The bactericidal capacity was determined with a standard test by using Escherichia coli. Both types of films had an estimated charge density in the order of 1016 positive charges per cm2; P4VP films removed about 95–99% of bacteria, whereas 4PVPQ films eliminated 100%. The methodology proposed for the synthesis of antibacterial polymer coatings is simpler, faster, and more environmentally friendly than other plasma-based methods; operation at Troom and Patm may also have a significant effect on the economics and the ease of implementation of the process at commercial scale. The suggested approach may facilitate the development of new universal coatings, and operating plasma conditions could be extrapolated for engineering antibacterial coatings in industrial areas where bacterial attachment is of concern.
MHO thanks Consejo Nacional de Ciencia y Tecnología (CONACyT) scholarship 228888. The financial support of CONACYT (Grants 162651 and 252320) and UASLP (Grant C13-FRC-01-04-04) for the development of the project is greatly appreciated The authors thank Rosa E. Delgado-Portales for supplying the E. coli 11775 strain, and Claudia Arellano del Rio, Maria de Lourdes González-González, Claudia Guadalupe Elías, Gladis Judith Labrada-Delgado and Maria Estela Nunez-Pastrana for technical support.
Compliance with ethical standards
Conflict of interest
Authors declare no conflict of interest.
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