Concurrent selective laser sintering and graphitization of polyimide microparticles into functional and flexible 3D structures for energy storage and sensing

Selective laser sintering (SLS) is an emerging technology for the fabrication of 3D complex polymeric structures by sintering polymer microparticles. But its application is constrained by the limited material selection and functionality of the polymer microparticles. To address this major challenge, here we creatively integrate SLS with polyimide and its hybrid microparticles, so that concurrent SLS and graphitization enables the precise fabrication of 2D/3D patterned and conductive graphene structures. By chemically modifying the polyimide microparticles with metal salt precursors, 3D graphene-FeO_x hybrid structures with precisely controlled geometry can be achieved after SLS. Furthermore, by sequential SLS with two types of polymer microparticles, such as thermoplastic polyurethane and polyimide, 3D soft and flexible structures with a conductive graphene coating can be conveniently fabricated. We also demonstrate promising applications of such 2D/3D hybrid structures in energy storage and strain sensors. The electrochemical capacitance or electrical responses can be widely tuned by controlling the SLS fabrication process and parameters. Our approach provides a new and versatile platform for the advanced manufacturing of soft and conductive 2D/3D structures with promising applications in energy and electronics.