Fluorine-Free Transparent Antifouling Polymer Coatings for Consumer Electronics via Double Latent Post-Crosslinking Strategy

Abstract Given that daily used electronic devices like mobile phones and tablets are frequently exposed to complex environments possibly involving pathogens and contaminants, posing a potential risk of disease transmission, the development of antifouling and antibacterial coatings tailored to the hygiene requirements of these devices is of significant importance. Herein, disulfide-containing cationic polydimethylsiloxane (PDMS)-modified polyurethanes (CxSiyPUs) were designed via integrating low-surface-energy PDMS segments, quaternary ammonium antibacterial units, and labile disulfide bonds for post-cross-linking. Waterborne CxSiyPU (WCxSiyPU) emulsions were prepared via self-emulsification, yielding CxSiyPU nanoparticles with spherical morphology, controllable particle size, and positively charged surfaces. Leveraging the latent nature of disulfide bonds, a latent isocyanate post-cross-linker was directly introduced into the WCxSiyPU emulsion to form a one-component emulsion, which enhanced storage stability and facilitated subsequent application. During thermal curing, disulfide bonds underwent homolytic cleavage and captured hydrogen atoms to generate thiol groups, which further reacted with released isocyanate groups to form thiocarbamate cross-links, realizing post-cross-linking via a double latent reaction strategy. The CxSiyPU coatings displayed an ultrasmooth, amorphous, hydrophobic surface with enriched PDMS moieties, possessing low surface energy, superior resistance to bacterial attachment, excellent optical transparency, and room-temperature hydrophobic recovery ability. Furthermore, the optimal coating delivered favorable cyclic antibacterial durability under repeated water immersion, high surface hardness, good mechanical abrasion and peeling resistance, and robust substrate adhesion, verifying its possible long-term service performance in daily use scenarios. The CxSiyPU coatings integrated excellent antipollution with preserved optical transparency and interactive performance, making them highly promising for transparent, hygienic, protective applications for consumer electronics to minimize the risk of disease transmission.