4D printing of thermal responsive structure for environmentally adaptive radiative cooling and heating

AbstractFourdimensional (4D) printing, which combines a threedimensional (3D) printing process with dynamic modulation of materials, provides a possible solution to achieve stimuliresponsive microstructure that exhibit more complex functionality. One of the potential applications for these stimuliresponsive hydrogels is switchable passive radiative cooling and warming. However, most current attempts are limited to monofunctionality, either radiative cooling or warming only. In this article, we demonstrate a doubleside morphing flower structure for a dual functionality, switchable cooling or warming dependent on the environment. The morphing structure was designed with the aid of emissivity calculations and then fabricated by the 3D printing method. The transition between openflower and closeflower states occurs at 32C within a minute, resulting in ~35% emissivity difference between these two states. As a result, the power difference between inner layer and outer layer was as high as 22W/m2 which is a function of pyramid bottom size.

4D printing of thermal responsive structure for environmentally adaptive radiative cooling and heating Academic Article