Environmentally-friendly, low-cost, and easy superhydrophilic and underwater superoleophobic cement-coated meshes were developed to separate oil/water mixtures.

Superhydrophobic flexible strain sensors have great application value in the fields of personal health monitoring, human motion detection, and soft robotics due to their good flexibility and high sensitivity. However, complicated preparation processes and costly processing procedures have limited their development. To overcome these limitations, in this work we develop a facile and low-cost method for fabricating superhydrophobic flexible strain sensor via spraying carbon black (CB) nanoparticles dispersed in a thermoplastic elastomer (SEBS) solution on a polydimethylsiloxane (PDMS) flexible substrate. The prepared strain sensor had a large water contact angle of 153 ± 2.83° and a small rolling angle of 8.5 ± 1.04°, and exhibited excellent self-cleaning property. Due to the excellent superhydrophobicity, aqueous acid, salt, and alkali could quickly roll off the flexible strain sensor. In addition, the sensor showed excellent sensitivity (gauge factor (GF) of 5.4–7.35), wide sensing ranges (stretching: over 70%), good linearity (three linear regions), low hysteresis (hysteresis error of 4.8%), and a stable response over 100 stretching-releasing cycles. Moreover, the sensor was also capable of effectively detecting human motion signals like finger bending and wrist bending, showing promising application prospects in wearable electronic devices, personalized health monitoring, etc.

An effective solution to separate oil and water is urgently needed owing to the increasingly serious problem of oil pollution. Numerous studies have been done to endow ordinary materials with extreme wettability for oil/water separation. Unfortunately, most of these materials cannot work in harsh environments, resulting in the low stability and practicability in practice. Herein, a facile method was proposed to fabricate superhydrophilic and underwater superoleophobic mesh by immersing ordinary mesh in a mixture of sulfuric acid (H₂SO₄) and chromium trioxide (CrO₃). After immersing for just 1 min, the mesh was endowed with superhydrophilicity (CA = 0°) and underwater superoleophobicity (hexane CA = 151°, SA = 14°). Increasing the immersion time to 3 min, the prepared mesh exhibited better superoleophobicity. A separation device was developed based on the prepared mesh and the separation efficiencies for diverse oil/water mixtures containing acid, alkaline, salt and hot water were above 95%. The device retained a high efficiency after being reused for 20 times and the prepared mesh maintained superoleophobicity after immersing underwater for 72 h and abrasion test of 100 cycles. This oil/water separation method is easy-to-use, inexpensive, power-free and it can be used to separate caustic oil/water mixtures.

Passive-cooling building materials can achieve cooling without external energy consumption, which is an energy-saving and environmentally friendly cooling method. However, the existing passive-cooling building materials have the limitations of high cost, complicated processes, and a toxic organic solvent, which hinders the passive-cooling technology applied in practical building. To overcome these limitations, we developed a facile, high-efficiency, non-toxic, and superhydrophobic passive-cooling building coating (SPCBC) with an efficient cooling capability and excellent durability that was composed of polydimethylsiloxane and SiO₂. The fabricated SPCBC demonstrated a high reflectance and a high emittance, showing a superior cooling capability with a 14 °C temperature drop compared with a bare cement surface on a hot summer day. In addition, the SPCBC could not be wetted or contaminated by muddy water, corrosive aqueous solutions, or dust, which presented an excellent anti-fouling and self-cleaning capability. Moreover, the fabricated SPCBC could work outdoors for 30 days, withstand UV irradiation for 30 days, and resist accelerated aging for 100 h without any significant changes in the superhydrophobicity and the cooling capability, meaning that the SPCBC had an outstanding durability. This work provides a new method to facilitate passive-cooling technology to apply in practical building in hot weather regions of the world.