No abstract

A unique, durable, nonleaching antimicrobial urethane coating possessing energy-dampening properties is reported. Five novel diol-functionalized quaternary ammonium bromide salts were designed, synthesized, and cross-linked with a commercial polyisocyanate to afford novel multifunctional self-decontaminating coatings. Leaching of the antimicrobial into the environment is eliminated because of the biocidal tether. The effectiveness of these molecules to self-concentrate at the air–polymer interface without addition of other surface modifying additives proved extremely advantageous, and consequently resulted in microphase separation as confirmed by AFM. The coatings were designed to continuously decontaminate against a variety of pathogenic bacteria in addition to affording preliminary dampening properties. Minimum inhibitory concentration studies as well as surface antimicrobial evaluations were conducted using both Gram-positive and Gram-negative bacteria. Additionally, viscoelastic properties, hardness, tack, and surface energy measurements were used to correlate with coating performance.

A variety of amphiphilic quaternary dimethylammonium compounds bearing n-alkyl and oxyethylene groups have been designed and synthesized as antimicrobial additives for use in self-decontaminating surfaces. The effectiveness of these additives stems from a unique ability to self-concentrate at the air-polymer interface without the incorporation of exotic perfluorinated or polymeric functionalities. X-ray photoelectron spectroscopy analysis reveals surface enrichment as high as 18-fold, providing a 7-log reduction of both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The migration to the surface is a consequence of the hydrophobicity of the additive within the hydrophilic polyurethane resin, over which an unprecedented level of control can be exerted by altering the lengths of the n-alkyl and oxyethylene groups. Thus, for the first time, specific surface and bulk coating concentrations can be achieved as desired using a single class of antimicrobial additives.

The adhesive properties, as measured by bulk tack analysis, are found to decrease in blends of isomerically pure Sc3N@Ih-C80 metallic nitride fullerene (MNF) and polystyrene-block-polyisoprene-block-polystyrene (SIS) copolymer pressure sensitive adhesive (PSA) under white light irradiation in air. Reduction of tack is attributed to the in-situ generation of 1O2 and subsequent photooxidative crosslinking of the adhesive film. Comparisons are drawn to classical fullerenes C60 and C70 for this process. This work represents the first demonstration of 1O2 generating ability in the general class of metallic nitride fullerenes, (M3N@C80). Additional support is provided for the sensitizing ability of Sc3N@Ih-C80 through the successful photooxygenation of 2-methyl-2-butene to its allylic hydroperoxides in benzene-d6 under irradiation at 420 nm, a process which occurs at a comparable rate to C60. Photooxygenation of 2-methyl-2-butene is found to be influenced by the fullerene sensitizer concentration and oxygen gas flow rate. Molar extinction coefficients are reported for Sc3N@Ih-C80 at 420 nm and 536 nm. Evaluation of the potential antimicrobial activity of films prepared in this study stemming from the in-situ generation of 1O2 led to an observed 1 log kill for select Gram-positive and Gram-negative bacteria.

With the increase in antibiotic-resistant microbes, the production of self-decontaminating surfaces has become an area of research that has seen a surge of interest in recent years. Such surfaces, when incorporated into commercial products such as children's toys, medical devices and hospital surfaces could reduce the number of infections caused by pathogenic microorganisms. A number of active components for self-decontaminating surfaces have been investigated, including common antibiotics, metal ions, quaternary ammonium salts (QAS), and antimicrobial peptides (AMP). A recent research focus has been development of a wide range of amphiphilic antimicrobial additives that when combined with modern low volatile organic compound (VOC), water-based paints leads to a surface concentration of the active compounds as the coating cures. Herein we report the development of antimicrobial coatings containing a variety of additives, both QAS and AMP that are active against a broad-spectrum of potentially pathogenic bacteria (1-7 log kill), as well as enveloped viruses (2-7 log kill) and fungi (1-2 log kill). Additionally, these additives were compatible with water-dispersed acrylate coatings (latex paint) which have a broad range of real world applicability, and remained active for multiple challenges and when exposed to various cleaning scenarios in which they might encounter in real world situations.