A Paraffin‐Based Photoresin: 3D Printing of Paraffin for Encapsulation‐Free Shape‐Stabilized Paraffin‐Based Phase Change Materials

Abstract High‐resolution structuring of paraffin wax as phase change material is essential for miniaturized applications in thermal actuators, flexible electronics, and sensors, yet requires complex encapsulation methods that limit design freedom and increase costs. A low‐cost encapsulation‐free approach is demonstrated for preparing shape‐stabilized paraffin‐based phase change materials using digital light processing based 3D printing. In this work, a paraffin‐loaded photoresin with paraffin concentrations up to 60 wt.% in acrylated polymer networks. The printed parts are thermally responsive undergoing a shape‐stabilized phase change, and exhibits elastic and stretchable properties. Despite the high paraffin loading, the printed parts can be stretched up to 130% in length. Differential scanning calorimetry results show that the highest phase change latent heat of the printed parts can reach 120 J · g⁻¹. Cyclic scanning differential calorimetry results show a slight shift in endothermic and exothermic signals indicating no obvious paraffin leakage. Considering that the phase transition of the paraffin in the photoresin at the melting point of paraffin affects the mechanical modulus of the printed parts, a pneumatic actuator is also printed that responds to body temperature. This work contributes a significant step toward a wide range of applications from micro sensors to new interactive soft actuators.