Selective Laser Sintering for Electrically Conductive Poly(dimethylsiloxane) Composites with Self-Healing Lattice Structures

Developing flexible elastomer composites for sensors and effective fabrication methods is of great significance. Single-walled carbon nanotubes (SWCNTs)-wrapped poly(dimethylsiloxane) covalent adaptable networks (PDMS-CANs) composite powders were prepared through a liquid-phase deposition and adsorption process and used for selective laser sintering (SLS) three-dimensional (3D) printing. The electrically conductive PDMS composite parts with self-healing lattice structures were printed. Ingeniously utilizing the quasi-static processing characteristic of SLS printing, the conductive segregated SWCNT networks are in situ formed in PDMS-CANs during the printing process, showing an ultralow percolation threshold of 0.007 wt %. Due to the photothermal and electrothermal effects of SWCNTs, the composites possess multifunctions including crack diagnosis and self-healing triggered by heat, electricity, or light. To demonstrate the potential application, the SLS-printed SWCNTs@PDMS-CANs strain sensors with various lattice structures were designed and SLS-printed. Their strain sensitivity is compared and analyzed by finite element modeling. The results show that the TPMS Schwartz structure possesses the highest sensitivity due to the concentrated localized strain.