Versatile Antireflection Coating for Plastics: Partial Embedding of Mesoporous Silica Nanoparticles onto Substrate Surface.

Antireflection (AR) coating for transparent plastic substrates is constructed by partially embedding mesoporous silica nanoparticles (MSNs) onto the surface of the substrates. Simulation of optical properties of polymer substrates coated with a single-particle MSN layer indicates that the surface has a low and graded refractive index in the direction of the thickness and effectively decreases the reflectance of visible light. The MSN-coated surfaces can be prepared by exposure of the MSN-painted substrates to a solvent vapor, irrespective of the shape of the polymer substrates. The plastic substrates with a single-particle layer of MSNs with diameters of 145-165 nm exhibit high transparency and good AR behavior as simulated. The mesoporous structures of MSNs play important roles not only in decreasing the refractive index but also in strengthening the adhesion between MSNs and substrate surfaces. Moreover, fixation of MSNs onto a thermosetting epoxy resin is successfully achieved by transfer of a single layer of MSNs from flexible films for which MSNs are weakly bonded. The present simple AR coating is applicable to a wide range of substrates with various materials and shapes, and useful for various applications such as optical devices, displays, and solar cells.