Ordered-Porous-Array Polymethyl Methacrylate Films for Radiative Cooling

Abstract

Passive radiative cooling is a spontaneous pattern of reflecting sunlight and radiating heat into the cold outer space through transparent atmosphere windows. In this work, an ordered-porous-array polymethyl methacrylate (OPA-PMMA) film with the properties of excellent radiative cooling is designed and studied. An ultra-high emissivity of 98.4% in the mid-infrared region (3–25 μm) and a good solar reflectance of 85% in the ultraviolet and near-infrared solar spectra (0.2–2.5 μm) were achieved. The surface temperature of the OPA-PMMA film is 16 °C lower than that of the smooth-surface PMMA films and is 8.6 °C lower than that of the commercial white paint in the outdoor test. The structure of the OPA plays an important role in improving solar reflectivity and emissivity. The films are fabricated using a one-step low-cost process that can be applied for large-scale production. It is vital for promoting radiative cooling as a viable energy technology for buildings, fabric, or equipment that need a cooling environment.

Low-cost and scalable sub-ambient radiative cooling porous films

“…The foam box was made of insulated polystyrene and covered with aluminum foil to reflect sunlight and radiative from the surrounding environment. We placed the sample in the cavity at the top of the foam box and covered the top of the foam box with a low-density polyethylene film with a distance of ∼3 mm between the sample and the PE film to insulate it from the effects of external air convection 28 . The foam box was placed on the roof of a 12-m-high building in Wuhan, China, to avoid the test setup being blocked by other buildings and trees.…”

“…We placed the sample in the cavity at the top of the foam box and covered the top of the foam box with a low-density polyethylene film with a distance of ∼3 mm between the sample and the PE film to insulate it from the effects of external air convection. 28 The foam box was placed on the roof of a 12-m-high building in Wuhan, China, to avoid the test setup being blocked by other buildings and trees. A 4-channel K-type thermocouple was used to record the temperature of the sample, the inside of the foam box, and the external environment of the foam box.…”

Polymer composites with hierarchical architecture and dielectric particles for efficient daytime subambient radiative cooling

“…For example, under standard solar irradiance (1000 W m −2 ), the radiant heat ux is much higher than the sum (z170 W m −2 ) of a blackbody at 303 K, the outer space at ∼3 K, and the air at 303 K, then the solar reectance of the cooler increases by 1%, solar power reected is ∼10 W m −2 , and the cooling temperature increases by z1 K. 19 Unfortunately, many of the coolers are limited by unsatisfactory solar reection, which leads to high solar absorption beyond infrared emission and therefore reduces the cooling effect. [20][21][22] Over the past few years, tremendous work has been devoted to designing high-performance PDRC materials in order to advance efficient cooling performance, such as photonic structure metamaterials, 11,[23][24][25][26][27] nanoparticle-based radiators, 9,28,29 plastic textiles, 14,30 and structural woods. 31 However, many of them usually require a complicated synthesis process and high manufacturing costs, which severely limits large-scale application and promotion.…”

“…For example, under standard solar irradiance (1000 W m −2 ), the radiant heat flux is much higher than the sum (≈170 W m −2 ) of a blackbody at 303 K, the outer space at ∼3 K, and the air at 303 K, then the solar reflectance of the cooler increases by 1%, solar power reflected is ∼10 W m −2 , and the cooling temperature increases by ≈1 K. 19 Unfortunately, many of the coolers are limited by unsatisfactory solar reflection, which leads to high solar absorption beyond infrared emission and therefore reduces the cooling effect. 20–22…”

Visible Light Induced Degradation of Poly(methyl methacrylate‐co‐methyl α‐chloro acrylate) Copolymer at Ambient Temperature

“…[ 1–3 ] Cost‐effective, transparent, and lightweight nature of PMMA combined with excellent resistance to environmental conditions and scratches makes it a suitable alternative for a variety of indoor and outdoor applications. [ 4–11 ] Hence, the demand for PMMA production in the industry has been consistently increasing per year. [ 12,13 ] According to statistics, PMMA consumption is expected to reach up to around 4 M tons in 2027.…”