Optimization of in situ synthesis of Ag/PU nanocomposites using response surface methodology for self-disinfecting coatings

Abstract

Abstract This study deals with the development and optimization of the in situ synthesis of Ag/polyurethane (PU) nanocomposites with superior antimicrobial activities and minimal color changes using a central composite design (CCD) in conjunction with response surface methodology (RSM). The experimental design was to evaluate the effects of two independent variables: (1) AgNO 3 content ( X 1 ) and (2) DMF content ( X 2 ) on the measured responses, i.e., the %reduction of Escherichia coli ( Y 1 , %), %reduction of Staphylococcus aureus ( Y 2 , %), and the color differences of nanocomposites ( Y 3 , Δ E *). The formation of Ag nanoparticles (AgNPs) in UV-curable PU matrix was determined by UV–vis absorption spectroscopy, Field Emission Scanning Electron Microscope (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). Statistical analyses indicated the empirical second-order polynomial can accurately describe the %reduction of E. coli , %reduction of S. aureus , and color difference values. The 3D response surface graphs showed that the optimal contents of AgNO 3 and DMF were 0.3 and 36.0 phr, respectively. We have demonstrated that RSM can be used to determine the optimal conditions for in situ synthesis of AgNPs in a UV-curable PU matrix for the development of self-disinfecting coatings. Therefore, the application of RSM for determining optimal formulations for self-disinfecting coatings with excellent antibacterial activities and minimal color changes is effective and practical.