The oily wastewater generated in the industrial field is adversely affecting the environment, while the current methods for oil–water separation are complex and costly. Therefore, it is significant to use low cost and environmentally friendly materials to prepare a smart responsive superhydrophobic coating for the effective separation of oil–water mixtures. In this paper, a fluorine-free copolymer with pH responsiveness was fabricated by a solution impregnation method, and it was compounded by silica nanoparticles/polydimethylsiloxane to prepare a superhydrophobic coating on the paper and cotton fabric. The prepared superhydrophobic coating remained in the superhydrophobic state after the alkali treatment, while it would be converted into the hydrophilic state after the acid treatment. Therefore, the pH-responsive superhydrophobic coating will be applied in controlled selective oil–water separation.

Hydrogel-based flexible electronic devices have great potential in human motion monitoring, electronic skins, and human-computer interaction applications; hence, the efficient preparation of highly sensitive hydrogel-based flexible sensors is important. In the present work, the ultrafast polymerization of a hydrogel (1–3 min) was achieved by constructing a tannic acid (TA)-Fe³⁺ dynamic redox system, which endowed the hydrogel with good adhesion performance (the adhesion strength in wood was 17.646 kPa). In addition, the uniform dispersal ensured by incorporating polydopamine-decorated polypyrrole (PPy@PDA) into the hydrogel matrix significantly improved the hydrogel’s stretching ability (575.082%). The as-prepared PAM/CS/PPy@PDA/TA hydrogel-based flexible sensor had a high-fidelity low detection limit (strain = 1%), high sensitivity at small strains (GF = 5.311 at strain = 0–8%), and fast response time (0.33 s) and recovery time (0.25 s), and it was reliably applied to accurate human motion monitoring and handwriting recognition. The PAM/CS/PPy@PDA/TA hydrogel opens new horizons for wearable electronic devices, electronic skins, and human-computer interaction applications.

Solid polymer electrolyte (SPE) is an important part of printed electrochemical gas sensors and are of value to electrochemical sensors. Here, a new type of SPE was prepared by dissolving a poly-vinylidene fluoride (PVDF) matrix in a 1-methyl-2-pyrrolidone (NMP) to immobilize 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM] [BF₄]), which was then used in a new electrochemical amperometric nitrogen dioxide sensor. The SPE was coated on a single electrode and attached to the electrode to construct a simple two-layer structure. Nitrogen dioxide in the air was reduced on the working electrode at a bias voltage of −500 V. We controlled the components and process parameters separately for control experiments. The results show that the SPE based on [EMIM] [BF₄], NMP, and PVDF coated on the electrode at a thickness of 1.25 mm with a 1:1:4 weight ratio under heat treatment conditions of 80°C for 2 min has the best sensitivity. The FTIR and XPS results indicated that SPE is prepared via physical miscibility. The SEM and XRD results showed that the sensitivity of the sensor is strongly dependent on the interconnected pore structure in SPE, and the pore structure is related to the synthesis ratio, morphology, and heat treatment mode of SPE. Moreover, the sensor sensitivity has a certain relationship with SPE conductivity. The reaction principle and cycle performance of the sensor were also studied.