Fabrication of the durable low refractive index thin film with chitin-nanofiber by LBL method

Durable low refractive index thin films with anti-reflection properties were successfully fabricated using chitin nanofibers (CHINF) obtained from crab shell. The low refractive index film was achieved by forming porous thin films; the porosity was produced by increasing the number of airspaces inside the membrane. The layer-by-layer (LBL) method was used to achieve the effective stacking of the CHINF. The influence of surface structure and refractive index under changes in the solution pH was investigated using scanning electron microscopy and ellipsometry. Transmittance of the fabricated film is 4.1 % higher than that of a glass substrate and refractive index film of that is 1.29. The films had abrasion resistance and antifogging properties because of the high mechanical strength and hydrophilicity of chitin. We believe this LBL film using CHINF is a promising candidate material to overcome the durability problems associated with optical thin films.