Synthesis and Characterization of Biocides and Study of their application in Emulsion Paints

Abstract

Between the two devised biocides, namely, metal dithizones and ZnO/amine composites, ZnO/propandiol, as a more environmental safe additive, was proved to be the most suitable biocide to emulsion acrylic paints, producing an antimicrobial agent equivalent or superseding the commercial available emulsion acrylic paints, due to its ability to sustain the alleged active oxygen species regarded as responsible for the biological cell damaging. Results interpretation indicate the importance of hydroxyl group’s presence of the amine additive which might support the active oxygen production sought mechanism when compared to other amine groups that might hinder such effect in addition to those present by the polymeric acrylic paint chains. The TEM images of the nano ZnO particles and its amine composites exhibited the role of the amine type on the nano ZnO particles agglomeration or dispersion which affects directly its biological activity related partially to the available active sites produced. Amine aromaticity was also concluded to hinder ZnO/amine composite activity towards microorganism cell destruction due may be to an increased liability for the active oxygen species conformation considered responsible for the microbiological cause. The same rule could apply to the ZnO/triazole (T) additive rather of its dispersion role towards ZnO particles and its specific microorganisms attack function compared to the PD amine when functioning in presence of ZnO. Accordingly, it should be concluded that equilibrium between the nano ZnO particles size, their dispersion form, amine ability to stabilize active produced oxygen, type of bacteria microorganisms should all be counted for when persistence of antimicrobial agent efficiency is regarded. Most of the additives used acquire antimicrobial activity toward Gram –ve microorganisms higher than that toward Gram +ve microorganisms which is more favorable at surgical rooms due to many available infections at surgical rooms caused mainly by Gram –ve microorganisms. The accelerated climate ageing of emulsion polyacrylic based paint films containing ZnO/PD conducted upon exposure to the artificial weathering environments, the polymeric matrix photooxidized with formation of oxidation products. When the oxidation products are still trapped in coating, higher amounts of carbonyl and hydroxyl groups were found. The amount of carbonylic group's deformation was found lower than that produced by virgin acrylic paint which indicates that the nanocomposites formulated with the nanoparticles ZnO is showing higher photostabilisation behavior. In addition to the effective role as antimicrobial coat function, the ZnO/amine composites and dithizone complexes proved to prevail still their function as in-can preservatives even in the presence of cellulosic entities or its derivatives as paints thickening agents. The use of devised biocides as antimicrobial agent in dry film and as in-can preservatives; on large; are of valuable economic importance to both manufacturers and end users. It must be, however, noted that the application of such devised biocides are only regarded to the emulsion acrylic paints (waterborne) that should not be conflicted with those of oilborne due to the importance of hydroxyl groups availability as the controlling parameter.