Stiffness-variable polymers have found their enormous potential in practical applications that require automatic adaptation and modulation. However, prevailing materials are often constrained by specific operational triggers, limited mechanical responsiveness, and inadequate universality. In this study, drawing inspiration from the mechanism of non-solvent induced phase separation (NIPS), a novel series of polymers exhibiting reversible water-triggered stiffening is designed and synthesized by covalently incorporating poly(ethylene glycol) (PEG) as a non-solvent mediator onto the hydrophobic poly(meth)acrylates backbones. Owing to the hydrophilicity difference between PEG sidechains and backbones, these polymers display swift and substantial alterations in stiffness, with large-scale and regulable changes (from several-fold to exceeding 200-fold) upon water penetration, resulting from water-induced microphase separation. Meanwhile, the polymers also possess intrinsic dual-responsive shape-memory properties. Due to the excellent commercial availability, versatility, and designability of these polymers, the work provides novel perspectives for the advancement of water-triggered stiffening materials and opens avenues for their prospective applications in various domains.
Pressure sensors still face the challenge of combining high sensitivity with a wide detection range. In this study, we designed a tension–compression conversion structure and combined it with a variable stiffness design strategy to fabricate pressure-sensing devices. The structure can convert the sensing properties of two-dimensional (2D) stretchable materials into the sensing properties of 3D compressible devices. The sensing and mechanical properties can be designed through simulations and theoretical calculations. The slope structure provides linear sensing within 24.3 N. The variable stiffness design strategy enables the sensor to sense a small load with high sensitivity (3.5 N −1 ) with a wide pressure range (0.002–24.3 N, with an extended range of 82.6 N). In addition, the sensing structure can work stably in an underwater environment. This design strategy of using 2D stretchable strain sensors as the sensing unit to develop a compression sensor device will provide new ideas for future sensor design.
危险品化学品经营许可证（带存储）