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

Abstract

© 2017 Elsevier B.V. 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) AgNO3 content (X1) and (2) DMF content (X2) on the measured responses, i.e., the %reduction of Escherichia coli (Y1, %), %reduction of Staphylococcus aureus (Y2, %), and the color differences of nanocomposites (Y3, ΔE*). 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 AgNO3 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.