Synthesis of Surface-Reinforced Biodegradable Chitosan Nanoparticles and Their Application in Nanostructured Antireflective and Self-Cleaning Surfaces

Surface-reinforced chitosan nanoparticles were used instead of polystyrene nanoparticles in the nanostructuring of antireflective, self-cleaning surfaces. Nanosphere lithography is a fascinating method to fabricate functional surfaces, but a large amount of nanoparticles are used and drained. Because synthetic polymer nanoparticles cause serious ecological and biological problems, the preparation of spherical nanoparticles was attempted with biodegradable, natural polymers, including chitosan and cellulose for application in nanosphere lithography. Chitosan nanospheres can be formed with a controlled size and surface charge, whereas cellulose spherical nanoparticles are hard to make. Therefore, chitosan nanoparticles were chosen and enclosed with trichloro(phenyl)silane to enhance their stability under plasma etching. A monolayer of the surface-reinforced chitosan nanoparticles was coated on a glass surface via a floating method for nanosphere lithography to act as a mask under reactive ion etching. After etching, the nanostructured glass showed a 2% increased transmittance compared with bare glass at 550 nm due to an antireflective effect. Moreover, the nanostructured glass with perfluoropolyether coating had a water contact angle of 152 degrees and exhibited superhydrophobicity and a self-cleaning effect. This work addresses the issues of ecofriendly nanostructuring based on biodegradable, natural polymer nanoparticles for energy- and water-saving applications of nanostructured surfaces, by demonstrating the practical utilization of chitosan nanoparticles in nanosphere lithography.