Synthesis of VO2/Poly(MMA-co-dMEMUABr) antimicrobial/thermochromic dual-functional coatings

Abstract

In order to address the need for window coatings that can control room temperature while being self-cleaning, this work examined a dual-functional antimicrobial/thermochromic coating. The goal was addressed by chemically polymerizing the antimicrobial agent, quaternary ammonium compound (QAC) N,N-dimethyl-N-{2-[(2-methylprop-2-enoyl)oxy]ethyl}undecane-1-aminium bromide (dMEMUABr) while using vanadium dioxide (VO2) as the thermochromic agent. The antimicrobial agent dMEMUABr, having an acrylic moiety and a long hydrocarbon tail for enhanced killing, was synthesized and characterized by NMR and FTIR spectroscopies. VO2 nanoparticles were synthesized hydrothermally and characterized by physicochemical analysis including powder XRD, DSC and SEM. Polymer coatings were obtained by polymerizing dMEMUABr with methyl methacrylate (MMA) monomer under UV irradiation with the required UV curing time being investigated. Thermochromic performance of dual-functional VO2/poly(MMA-co-dMEMUABr) coating gave an infrared modulation ΔTIR of 5.8 % and luminous transmittance Tlum of 36.1 % at 25 °C. The antimicrobial testing of the dual-functional coating indicated that it could kill 90.3 % of bacteria Escherichia coli (E. coli) within 24 h at a low dMEMUABr concentration (3.8 wt % relative to MMA). The zone of inhibition test proved the contact kill principle of the coating, without releasing toxic antimicrobial agents to the environment.