All-Day Radiative Cooling with Superhydrophobic, Flourine-Free Polydimethylsiloxane-Embedded Porous Polyethylene Coating

A new outdoor measurement result from London has been added.
A prediction of the radiative cooling potential of the coating for major European cities has been made.
All figures have been refined.

Abstract

In this article, we introduce PolyCool, an all-organic, per- and polyfluoroalkyl substances (PFAS)-free coating designed for passive, all-day cooling applications. The coating utilizes porous polyethylene (PE), produced via a straightforward dip-coating and phase-inversion process, achieving a polydisperse pore size distribution that facilitates exceptional solar reflectance of 97.4%. To enhance its emissivity, polydimethylsiloxane (PDMS) particles synthesized through a green emulsification method, enabling scalable and size-controlled production, were incorporated. During a 36-hour continuous test in London, the developed coating achieved subambient temperature reductions of 2 °C under direct sunlight and 5.5 °C at night. These results were obtained without the use of convective shields, despite partial cloud coverage and humidity levels exceeding 40%. The radiative cooling potential of this coating has been estimated for 10 major European cities based on its spectral data and meteorological conditions. Additionally, the surface texturing of the coating enabled superhydrophobic properties, with a contact angle exceeding 160°. The coating also exhibited excellent ultraviolet (UV) resistance and can be applied to a range of substrates, including polymer films, aluminum foil, and wood, with minimal equipment and material costs.

Content

Author and article information

Journal

Title: ScienceOpen Preprints

Publisher: ScienceOpen

Publication date (Electronic preprint): 4 February 2025

Affiliations

[1 ] Department of Electronic and Electrical Engineering, University College London, London;

[2 ] Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Santiago, Chile;

[3 ] School of Optoelectronic Engineering, Xidian University, Xi’an 710071, Shaanxi;

[4 ] Chemistry Department, University College London, London;

[5 ] Mines Paris – PSL University, Centre Energie, Environnement et Procédés (CEEP), Paris; ENGIE Lab CRIGEN Research Center, Stains, France;

[6 ] Department of Physics, University of Cambridge, Cambridge;

[7 ] School of Built Environment, University of New South Wales, Sydney; School of Engineering and Technology, Central Queensland University, Sydney;

[8 ] School of Built Environment, University of New South Wales, Sydney;

[9 ] ENGIE Lab CRIGEN Research Center, Stains, France;

[10 ] Mines Paris – PSL University, Centre Energie, Environnement et Procédés (CEEP), Paris;

[11 ] Nanoengineered Systems Lab, UCL Mechanical Engineering, University College London, London;

Author notes

[* ]Email: i.papakonstantinou@ 123456ucl.ac.uk .

Author information

Lingxi Li https://orcid.org/0000-0003-3023-4302

Article

DOI: 10.14293/PR2199.000782.v2

SO-VID: 2afc1298-b8cf-45b6-81ca-d2e661790dff

License:

This work has been published open access under Creative Commons Attribution License CC BY 4.0 , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Conditions, terms of use and publishing policy can be found at www.scienceopen.com .

History

Date received : 25 March 2024

Funding

Funded by: funder-id , Royal Academy of Engineering Frontiers Research Grant;

Funded by: funder-id , ERC proof-of-concept;

Funded by: funder-id , UKRI;

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