Solar-Radiation-Dependent Anisotropic Thermal Management Device with Net Zero Energy from 4D Printing Shape Memory Polymer-Based Composites

Reports have pointed out that nearly 50% of the global total energy demand for buildings is used for daily heating and cooling. Therefore, it is very important to develop various high-performance thermal management techniques with low energy consumption. In this work, we present an intelligent shape memory polymers (SMPs)-based device with programmable anisotropic thermal conductivity fabricated by a 4D printing technique to assist in thermal management with net zero energy. Highly thermal conductive BN nanosheets were textured in a poly (lactic acid) (PLA) matrix by 3D printing, and the printed composites lamina exhibited significant anisotropic thermal conductivity. The direction of heat flow in devices could be switched programmably, accompanying the light-activated deformation controlled by grayscale of composite, which was demonstrated by the windows arrays composed of in-plate thermal conductivity facets and SMPs-based hinge joints, achieving the programmable movement of opening and closing under different light conditions. Based on solar radiation-dependent SMPs coupled with the adjustment of heat flow along anisotropic thermal conductivity, the 4D printed device has been proved in concept for potential applications in thermal management in a building envelop for dynamic climate adaptation, taking place automatically based on the environment.

Automated summary

Reports have highlighted the importance of developing high-performance thermal management techniques with low energy consumption, as almost 50% of energy used in buildings is devoted to heating and cooling. In this study, an intelligent shape memory polymers (SMPs)-based device with programmable anisotropic thermal conductivity was developed using 4D printing, to assist in thermal management with net zero energy. Through 3D printing, highly thermal conductive BN nanosheets were incorporated in a PLA matrix, resulting in composites with significant anisotropic thermal conductivity. The programmable movement of the device, including the switching of heat flow direction, was achieved through light-activated deformation controlled by the grayscale of the composite.