@article{2943e46771c144f6b07b645136362435,
title = "Porous Polymers with Switchable Optical Transmittance for Optical and Thermal Regulation",
abstract = "Adaptive control of broadband light is essential for diverse applications including building energy management and light modulation. Here, we present porous polymer coatings (PPCs), whose optical transmittance changes upon reversible wetting with common liquids, as a platform for optical management from solar to thermal wavelengths. In the solar wavelengths, reduction in optical scattering upon wetting changes PPCs from reflective to transparent. For poly(vinylidene fluoride-co-hexafluoropropene) PPCs, this corresponds to solar and visible transmittance changes of up to 0.74 and 0.80, respectively. For infrared (IR) transparent polyethylene PPCs, wetting causes an “icehouse-to-greenhouse” transition where solar transparency rises but thermal IR transparency falls. These performances are either unprecedented or rival or surpass those of notable optical switching (e.g., electrochromic and thermochromic) paradigms, making PPCs promising for large-scale optical and thermal management. Specifically, switchable sub-ambient radiative cooling (by 3.2°C) and above-ambient solar heating (by 21.4°C), color-neutral daylighting, and thermal camouflage are demonstrated.",
keywords = "daylighting, infrared, optical modulation, optical switching, porous polymers, radiative cooling, solar, solar heating, thermoregulation, transmittance switching",
author = "Jyotirmoy Mandal and Mingxin Jia and Adam Overvig and Yanke Fu and Eric Che and Nanfang Yu and Yuan Yang",
note = "Funding Information: This work was supported by startup funding from Columbia University, AFOSR (Y.Y. grant no. FA9550-18-1-0410), AFOSR MURI (Multidisciplinary University Research Initiative) program (N.Y. grant no. FA9550-14-1-0389), AFOSR DURIP (Defense University Research Instrumentation Program) (N.Y. grant no. FA9550-16-1-0322), and the National Science Foundation (N.Y. grant no. ECCS-1307948). J.M. acknowledges support from the Schmidt Science Fellows Program, in partnership with the Rhodes Trust. J.M. discovered the switchable solar transmittance of P(VdF-HFP) PPCs, extended the concept to PTFE and ethyl cellulose, and conceived and demonstrated switchability in thermal infrared wavelengths. J.M. and Y.Y. conceived applications and designed the experiments. J.M. conceived the design of PPC-air/liquid systems and chose polymer-liquid combinations. J.M. performed the simulations and theoretical calculations. M.J. J.M. Y.F. and E.C. designed the PPC-air/liquid systems. J.M. and A.O. performed the optical measurements. J.M. Y.Y. N.Y. and A.O. wrote the manuscript. A provisional patent (U.S. 62/596,145) has been filed related to this work. Funding Information: This work was supported by startup funding from Columbia University , AFOSR (Y.Y. grant no. FA9550-18-1-0410 ), AFOSR MURI (Multidisciplinary University Research Initiative) program (N.Y. grant no. FA9550-14-1-0389 ), AFOSR DURIP (Defense University Research Instrumentation Program) (N.Y. grant no. FA9550-16-1-0322 ), and the National Science Foundation (N.Y. grant no. ECCS-1307948 ). J.M. acknowledges support from the Schmidt Science Fellows Program , in partnership with the Rhodes Trust . Publisher Copyright: {\textcopyright} 2019 Elsevier Inc.",
year = "2019",
month = dec,
day = "18",
doi = "10.1016/j.joule.2019.09.016",
language = "English (US)",
volume = "3",
pages = "3088--3099",
journal = "Joule",
issn = "2542-4351",
publisher = "Cell Press",
number = "12",
}