Additive Manufacturing of High-Performance Engineering and Piezoelectric Polymers through Precipitation Printing

Abstract

Additive manufacturing (AM), or 3D printing of lightweight engineering polymers has become a crucial part in the industrial manufacturing process in the past two decades, which allows for scalable fabrication of complex geometries with cost and material efficiency. However, difficulties have arisen for the AM of high-performance (high-temperature) polymers and multifunctional piezoelectric polymers used in aerospace, automotive and electronic industries. Existing thermal energy-based AM processes such as material extrusion and powder bed fusion have limitations in the quality of produced high-performance polymers due to the huge thermal gradient and stress, and they cannot fabricate common piezoelectric polymers with thermodynamically unfavorable polar crystalline structures. Therefore, new AM processes can be developed to overcome these challenges in high-performance and piezoelectric polymers. In this dissertation, a novel solvent-based AM process, termed precipitation printing, is developed to enable AM of multiple high-performance engineering and piezoelectric polymers with tailorable porosity and mechanical properties. The proposed method utilizes the dissolution of a target polymer in a suitable solvent to form a printing solution, and the computer-controlled deposition of the printing solution in a non-solvent coagulation bath to induce precipitation and solidification of the target polymer and eventually build 3D structures. This precipitation printing process has been successfully applied to fabricate high-performance polymeric 3D structures made of polysulfone and aramid with exceptional thermal and mechanical properties, and highly piezoelectric poly(vinylidene fluoride) as vibration energy harvesters and stress/strain sensors. Finally, precipitation printing also plays an integral role in achieving our 3D printed artificial feathers with embedded aerodynamic sensing. In summary, precipitation printing provides a new concept and a solution to fill a gap in AM of high-performance and multifunctional structures.