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Abstract It is challenging to post-tune the sensitivity of a tactile force sensor. Herein, a facile method is reported to tailor the sensing properties of conductive polymer composites by utilizing the liquid-like property of dynamic polymer matrix at low strain rates. The idea is demonstrated using dynamic polymer composites (CB/dPDMS) made via evaporation-induced gelation of the suspending toluene solution of carbon black (CB) and acid-catalyzed dynamic polydimethylsiloxane (dPDMS). The dPDMS matrices allow CB to redistribute to change the sensitivity of materials at the liquid-like state, but exhibit typical solid-like behavior and thus can be used as strain sensors at normal strain rates. It is shown that the gauge factor of the polymer composites can be easily post-tuned from 1.4 to 51.5. In addition, the dynamic polymer matrices also endow the composites with interesting self-healing ability and recyclability. Therefore, it is envisioned that this method can be useful in the design of various novel tactile sensing materials for many applications.
Abstract Space cooling and heating currently result in huge amounts of energy consumption and various environmental problems. Herein, a switching strategy is described for efficient energy-saving cooling and heating based on the dynamic cavitation of silicone coatings that can be reversibly and continuously tuned from a highly porous state to a transparent solid. In the porous state, the coatings can achieve efficient solar reflection (93%) and long-wave infrared emission (94%) to induce a subambient temperature drop of about 5 °C in hot weather (≈35 °C). In the transparent solid state, the coatings allow active sunlight permeation (95%) to induce solar heating to raise the ambient temperature from 10 to 28 °C in cold weather. The coatings are made from commercially available, cheap materials via a facile, environmentally friendly method, and are durable, reversible, and patternable. They can be applied immediately to various existed objects including rigid substrates.
