Nanoporous films with designable porosity prepared with binary polymer latexes

Abstract

Porosity in efficiently packed nanoparticle films is limited. A process modifying particle film to introduce extra pores in self-assembled nanoparticle film is needed. We report here a method by the selective dissolution of sacrificial particles from the codeposited binary latex-particle film for the preparation of nanoporous film with designable porosity. Nanoporous films with porosity and refractive index tunable in the range of 33–86% and 1.37–1.07, respectively, on a poly(methyl methacrylate) (PMMA) substrate are prepared by spin-casting PMMA/polystyrene (PS) mixed latexes and selective removal of PS particles with cyclohexane after thermally treating the deposited particle film to enhance the adhesion on PMMA substrate. The nanoporous film on PMMA substrate prepared with PMMA/PS latexes in 1/1 weight ratio under the optimal condition exhibited ultra low reflectance of ∼0.02%. With smaller sized latex particles (25 nm and 22 nm for PMMA and PS, respectively), smooth nanoporous film on PMMA substrate with 99.95% of transmittance was prepared. The nanoporous structures on PMMA substrate are stable toward ultrasonic cleaning in water and resist to peeling with Scotch tape.