Columbia University

Jyotirmoy Mandal

Nanfang Yu

Yuan Yang

A structured material is provided that includes a substrate and a porous structured polymer layer disposed thereon. The porous structured polymer layer includes a plurality of voids, and has a high hemispherical reflectance a high a hemispherical thermal emittance. The structured material is thus particularly advantageous for cool-roof coatings, enabling surfaces coated by the material to stay cool, even under strong sunlight. The material can be produced via structuring of polymers in a mixture including a solvent and a non-solvent. Sequential evaporation of the solvent and the non-solvent provide a polymer layer with the plurality of voids.

Scalable method of fabricating structured polymers for passive daytime radiative cooling and other applications

A switchable light transmission module is disclosed that includes a substrate having a first surface defining at least part of an enclosed volume, a porous layer disposed on the first surface and in fluid communication with the enclosed volume, and a reservoir in fluid communication with the enclosed volume. The reservoir is configured to supply a fluid to the sealed volume such that the fluid contacts the porous layer. The fluid has a refractive index that is close to the refractive index of the porous layer, has a high wettability for the porous layer, and does not dissolve the porous layer. When in a dry state, voids in the porous layer are filled with air which has a much different refractive index than the porous layer itself, resulting in a surface that is reflective and not very transmissive. During wetting of the porous layer by the fluid, however, those voids are filled with the fluid, reducing the difference in refractive index across the polymer-fluid interfaces such that light scattering is negligible and the surface becomes light permeable.

Growing community of inventors

Chittagong, Bangladesh

Jyotirmoy Mandal