Researchers at the University of Sydney, in collaboration with Dewpoint Innovations, have engineered a porous polymer coating that can reflect as much as 97% of sunlight, dissipate heat into the atmosphere, and maintain surface temperatures up to 6 degrees cooler than the ambient air—even in direct sunlight. This mechanism fosters ideal conditions for atmospheric water vapor to transform into water droplets on these cooler surfaces, much like the condensation seen on a bathroom mirror.
Experimental equipment installed on the roof of the Sydney Nanoscience Hub. Image credit: University of Sydney.
Professor Chiara Neto from the University of Sydney stated: “This innovation not only advances cool roof coating technology, but also paves the way for sustainable, low-cost, decentralized freshwater sources—an essential requirement given the challenges of climate change and rising water scarcity.”
A six-month field study conducted on the roof of the Sydney Nanoscience Hub demonstrated that dew was collected for 32% of the year, enabling a sustainable and reliable water source even during dry spells.
Under optimal conditions, this coating can yield up to 390 mL of water per square meter daily—sufficient for a 12-square-meter home, meeting one person’s daily hydration needs.
This research illustrates the integration of passive cooling techniques and atmospheric moisture collection into scalable paint-like solutions.
The extensive collection area suggests that this coating could have diverse applications in various industries, including water supply for livestock, horticulture for premium crops, cooling through spraying, and hydrogen production.
Contrary to conventional white paints, the porous coatings utilizing polyvinylidene fluoride-co-hexafluoropropene (PVDF-HFP) do not depend on UV-reflective pigments like titanium dioxide.
Dr. Ming Chiu, Chief Technology Officer of Dewpoint Innovations, remarked, “Our design achieves superior reflectiveness through an internal porous structure, ensuring longevity without the environmental downsides of pigment-based coatings.”
“By eliminating UV-absorbing materials, we have surmounted traditional limitations of solar reflectance while avoiding glare from diffuse reflection.”
“This equilibrium between performance and visual comfort enhances its ease of integration and appeal for real-world applications.”
Throughout six months of outdoor examination, researchers documented minute-by-minute data on cooling and water collection, confirming solid performance that remained stable under the harsh Australian sun—unlike similar technologies that often degrade quickly.
In addition to water harvesting, these coatings could help mitigate urban heat islands, lower energy needs for air conditioning, and provide climate-resilient water sources for regions facing heightened heat and water stress.
“This research also challenges the notion that dew collection is confined to humid environments,” noted Professor Neto.
“While humid conditions are optimal, condensation can also occur in arid and semi-arid areas where humidity increases during the night.”
“It isn’t a substitute for rainfall; rather, it serves as a water source when other supplies are scarce.”
The team’s work was published in the October 30th issue of Advanced Functional Materials.
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Ming Chiu et al. A passive cooling paint-like coating to capture water from the atmosphere. Advanced Functional Materials published online October 30, 2025. doi: 10.1002/adfm.202519108
Source: www.sci.news
