Depositing silica/polyvinyl pyrrolidone coating on sodium copper chlorophyllin dyed cotton fabric for photofading inhibition

Abstract

Natural dyes’ mutual nature of being prone to photofading dramatically hinders their applications in the textile industry. Insulating coating with ability to prevent natural dyes from photofading is a solution to this issue. Basing on this principle, SiO2 nanoparticles (NPs) with the finest diameter of 50 nm were in-situ grown on the sodium copper chlorophyllin (SCC) dyed fabric pre-coated with polyvinyl pyrrolidone (PVP) to form a durable SiO2@PVP layer above the molecules of this natural dye, SCC. The SiO2@PVP layer is able to inhibit the photofading of SCC as the ΔE of the SiO2@PVP treated fabric caused by 10-h exposure to 300 W simulated sunlight irradiation is lowered by up to 52.6% when compared to the SCC dyed fabric. Results from finite element analysis proves the good electrical resistance of the SiO2@PVP layer while an approximately 77.6% decrease in the current density of the treated fabric was observed in the photocurrent response tests. By piecing the above results together, reduced generation of ROS is proposed as the explanation for the decline in the photofading rate of SCC covered by the SiO2@PVP layer. In addition, PVP successfully served as the bridge between the inorganic SiO2 NPs to the organic cotton substrate, leading to an improved wash fastness of the SiO2@PVP treated sample from 2‐3 to 4. The SiO2@PVP layer proposed in this study can serve the purpose of inhibiting the photofading of natural dyes over a prolonged period of time.