Lightweight and geometrically complex ceramics derived from 4D printed shape memory precursor with reconfigurability and programmability for sensing and actuation applications

There is growing interest in additive manufacturing (AM) of ceramics due to the feasibility of achieving geometrically complex shapes for various engineering applications. Polymer-derived ceramics (PDCs), pyrolyzed from polymeric ceramic precursors, act as a competitive material for ceramic AM with advantages such as easy processability, flexible designability, and relatively low sintering temperature. However, the functionality of preceramic polymers is far from being fully exploited, thus restricting the development and applications of 3D printed ceramics. Herein, a novel multifunctional preceramic polymer composite with reconfigurability and shape memory effect is synthesized. By tuning the material compositions, the precursor inks suitable for 4D printing are pyrolyzed into lightweight self-shaping ceramics, allowing complex geometries to be fabricated. The preceramic polymers undergo a stepwise partial-to-full crosslinking process to form interpenetrating polymer networks , resulting in reconfigurability where the as-printed parts can be transformed into shapes with higher complexity. Unlike traditional precursors with static shapes, the precursor here possesses shape memory capability ( T g  ∼ 95 °C). During the sintering process, the 3D printed precursor could successively undergo programmable active shape transformation with a high recovery ratio (∼100 %) and pyrolysis conversion into lightweight ceramics (1.05 g/cm 3 ). By exploring the semiconducting behavior of resulting ceramics, temperature sensors leveraging the advantages of reshaping are designed to detect the surface over a wide range (25–750 °C) with good conformability. The development of 4D printed reconfigurable and programmable precursors for the construction of complex ceramics enriches both the complexity and self-shaping capability of ceramics, allowing them to be applied as smart thermistors and deployable structures.