4D printing of temperature-responsive composites with programmable thermochromic deformation bifunctional

Abstract

4D printing of programmable stimulus-responsive multifunctional smart materials is an emerging technology. However, the vast majority of 4D printing approaches use polymer-based materials, and single respond to environmental stimuli (such as humidity, light or touch), which limits the scope of applications. Here, paraffin particles and thermochromic particles (T-PIGs) were mixed into silica gel to prepare shape-color double-responsive bifunctional smart materials. As functional particles of shape memory, paraffin particles change their shape during the solid-liquid phase transition after heating, stretching, and forming, the position containing paraffin retains the residual strain, resulting in a strain difference from other positions, which can cause a change in shape. And the change of shape can be edited repeatedly. The quantification of shape-color double-responsive was achieved simultaneously through proper parameter regulation. The direct ink writing (DIW) method was presented as a technique for fabrication of dual-responsive 4D printing composites in different patterns. The effects of the process parameters and temperature-responsive properties on the characteristics of 4D deformation and discoloration were investigated. The proposed temperature-responsive controllable color-changing deformation 4D printing method is expected to be applied in soft robotics, intelligent manufacturing, and other fields.