Smart patterned surfaces with programmable thermal emissivity and their design through combinatorial strategies

摘要

The emissivity of common materials remains constant with temperaturevariations, and cannot drastically change. However, it is possible to designits entire behaviour as a function of temperature, and to significantly modifythe thermal emissivity of a surface through the combination of differentmaterials and patterns. Here, we show that smart patterned surfaces consistingof smaller structures (motifs) may be designed to respond uniquely throughcombinatorial design strategies by transforming themselves from 2D to 3Dcomplex structures with a two-way shape memory effect. The smart surfaces canpassively manipulate thermal radiation without-the use of controllers and powersupplies-because their modus operandi has already been programmed andintegrated into their intrinsic characteristics; the environment provides theenergy required for their activation. Each motif emits thermal radiation in acertain manner, as it changes its geometry; however, the spatial distributionof these motifs causes them to interact with each other. Therefore, theircombination and interaction determine the global behaviour of the surfaces,thus enabling their a priori design. The emissivity behaviour is not random; itis determined by two fundamental parameters, namely the combination oforientations in which the motifs open (n-fold rotational symmetry (rn)) and thecombination of materials (colours) on the motifs; these generate functionswhich fully determine the dependency of the emissivity on the temperature.