Highly Transparent Ultrahigh- Molecular-Weight Polyethylene/MXene Films with Efficient UV Absorption for Light Conversion and Energy Savings

Abstract

Abstract Recently, the issue of energy and the environment has been a topic of widespread concern, and the rational use of energy, including both energy conversion from more sustainable energy sources and energy savings, is one of the primary means for achieving the goal of carbon neutrality. Polymer composites that incorporate two-dimensional materials, such as MXenes, and can be used in light conversion, have attracted particular interest, but their opaque appearance limits wider applications. For example, due to the high transparency to solar irradiation, windows are the energy-efficient components, accounting for nearly 51% of the total solar energy, which seriously aggravates interior energy consumption. Thus, it is desirable to develop a transparent film that can enhance light conversion in order to avoid the heat exchange and heighten windows’ energy-saving capability. Herein, we successfully developed a series of visible-light-transparent and UV-absorbing ultrahigh-molecular-weight polyethylene (UHMWPE) composite films by using a combination of Ti3C2Tx MXene as fillers and 2-(2H-Benzotriazol-2-yl)-4,6-ditertpentylphenol (BZT) as dispersant. These composite films could be quickly heated to 65°C under light irradiation of 400 mW cm-2 and maintained over 85% visible light transmittance as well as low haze (< 12%). Because of the efficient UV absorption by these films, the temperature inside a container completely covered with the optimal composite film was reduced by 6–7°C compared to that inside a container covered with bare glass, demonstrating the potential for these films to be used in energy-saving applications. In addition, the optimal composite film was predicted to provide cooling energy savings ranging from 31 to 61 MJ m-2 year-1 for a typical building in various conditions corresponding to the climate conditions of 12 cities worldwide; these energy savings account for approximately 3%-12% of the total annual cooling energy consumption of such a building. These results imply that these composite films have wide potential for use as transparent devices in new energy-related applications.