Surface-silanized glass nanofibers and aluminate nanoparticles as reinforcing agents for acrylic emulsion toward multifunctional stimuli-responsive composite coatings

Abstract

Smart waterborne coatings have shown various functions, such as afterglow photoluminescence, antimicrobial activity, water resistance, ultraviolet blocking, and anti-counterfeiting properties. However, photoluminescent organic agents have shown poor photostability and high cost. Additionally, waterborne acrylic coatings have shown poor mechanical properties. Herein, nanoparticles of rare-earth strontium aluminate (NRESA) and electrospun glass nanofibers (EGN) were used to strengthen the bulk of acrylic (ACR) coatings to develop smart products with mechanical reliability, hydrophobicity, ultraviolet blocking, and persistent photoluminescence. By physically integrating nano-scaled particles of RESA, colorless smart coatings of EGN@ACR were produced. Photoluminescence spectra showed that the transparent EGN@ACR changed its appearance to greenish when exposed to ultraviolet rays. Hybrids of EGN@ACR with trace amounts of NRESA showed fluorescence emission with instant reversibility. As the phosphor concentration in the EGN@ACR hybrids increased, afterglow photoluminescence with delayed reversibility was detected. When excited at 370 nm, the hybrid coatings displayed an emission band at 519 nm. The morphological analysis of NRESA by transmission electron microscopy (TEM) displayed diameters of 9–21 nm. After being prepared using electrospinning technology, glass nanofibers were introduced into acrylic emulsion coatings as a reinforcement agent. Scanning electron microscopic (SEM) analysis of EGN showed diameters of 70–120 nm. The smart coatings had better resistance to scratches as compared to the control sample of NRESA-free acrylic paint. A higher concentration of NRESA resulted in enhanced hydrophobicity and ultraviolet blocking.