Microgel-Guided MXene Assembly for High-Performance, Low-Solid Content Conductive Inks

Rapid evolution of smart devices necessitates high-performance, lightweight materials for effective electromagnetic interference (EMI) shielding. Ti₃C₂T MXene nanosheets are promising for such applications, yet the high solid content typically required for 3D-printable MXene inks limits their scalability and cost efficiency. In this study, we present an MXene-based ink with an ultralow solid content (0.1 vol %) and a high water content (up to 98 wt %) enabled by cross-linked poly(acrylic acid) Carbopol microgels. The microgels facilitate a jammed network, creating a percolated structure that allows MXene assembly at minimal concentrations and achieving the lowest reported solid content for MXene inks to date. The MXene/microgel hybrid ink demonstrates superior rheological properties, matching or surpassing existing formulations, and is readily extrudable for 3D printing complex structures and coatings. Following freeze-drying, the printed MXene aerogels exhibit an electrical conductivity of 360 S/m, an EMI shielding efficiency of 57 dB, and a compression modulus of 1750 kPa, all achieved at an ultralow density of 25 mg/cm³. This work provides a detailed analysis of the MXene/Carbopol ink's structure-processing-performance relationship, highlighting its transformative potential for scalable 3D printing of conductive, EMI shielding materials across diverse applications.