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Polydopamine (PDA)-based self-adhesive hydrogel sensors are extensively explored but it is still a challenge to construct PDA-based hydrogels by free radical polymerization. Herein, a new approach to construct self-adhesive hydrogels by conducting free radical polymerization in both aqueous phase and micelle phase is developed. The following two-phase polymerization processes account for the formation of the self-adhesive hydrogels. The first one is the polymerization of acrylamide (AM) and dopamine (DA) in aqueous phase to form adhesive component PAM-PDA (PAM, polyacrylamide; PDA, polydopamine). The second one is the polymerization of hydrophobic monomer 2-methoxyethyl acrylate (MEA) in micelles of an amphiphilic block copolymer Pluronic F127 diacrylate (F127DA). The poly(2-methoxyethyl acrylate) (PMEA) networks help to maintain the high robustness of the hydrogel. Because PMEA and PDA form in relatively separated phases, the inhibition effect of PDA on the free radical polymerization process of PMEA is weakened. Based on this mechanism, mechanically strong and adhesive hydrogels are achieved. The introduced ions during preparation process, such as Na + , OH - and K + , endow the resulting hydrogels ionic conductivity. Resistive strain sensor of the hydrogel achieves a high gauge factor (GF) of 5.26, a response time of 0.25 s and high sensing stability. Because of the adhesiveness, such hydrogel sensor can be applied as wearable sensors in monitoring various human motions. To further address the freezing and drying problems of the hydrogels, organohydrogels are constructed in glycerol-water mixed solvent. The organohydrogels exhibit outstanding anti-freezing property and moisture retention ability, and their adhesiveness is well maintained in subzero conditions. Capacitive pressure sensors of the organohydrogels possessing a GF of 2.05 kPa -1 , high sensing stability and reversibility, are demonstrated and explored in monitoring diverse human motions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Flexible electronic devices (FEDs) based on hydrogels are attracting increasing interest, but the fabrication of hydrogels for FEDs with adhesiveness and high robustness in harsh‐temperature conditions and long‐term use remains a challenge. Herein, glutinous‐rice‐inspired adhesive organohydrogels are developed by introducing amylopectin into a copolymer network through a "one‐pot" crosslinking procedure in a glycerol–water mixed solvent containing potassium chloride as the conductive ingredient. The organohydrogels exhibit excellent transparency (>90%), conductivity, stretchability, tensile strength, adhesiveness, anti‐freezing property, and moisture retention ability. The wearable strain sensor assembled from the organohydrogels achieves a wide working range, high sensitivity (gauge factor: 8.82), low response time, and excellent reversibility, and properly responds in harsh‐temperature conditions and long‐time storage (90 days). The strain sensor is further integrated with a Bluetooth transmitter and receiver for fabricating wireless wearable sensors. Notably, a sandwich‐structured capacitive pressure sensor with organohydrogels containing reliefs as electrodes records a new gauge factor of 9.43 kPa−1 and achieves a wide response range, low detection limit, and outstanding reversibility. Furthermore, detachable and durable batteries and all‐in‐one supercapacitors are also fabricated utilizing the organohydrogels as electrolytes. Overall, this work offers a strategy to fabricate adhesive organohydrogels for robust FEDs toward wearable sensing, power supply, and energy storage. [ABSTRACT FROM AUTHOR]

2-Phenylimidazole (2-PZ) and polymethyl acrylic glycidyl ester (PGMA) are performed to fabricate a novel microcapsule latent curing agent of 2-PZ/PGMA by solvent evaporation method with 2-PZ as the core material and PGMA as the shell material. A novel single-component 2-PZ/PGMA/epoxy adhesive is also prepared by mixing 2-PZ/PGMA with epoxy resin matrix. The 2-PZ/PGMA microcapsules are characterized using scanning electron microscopy and granulometer. The curing kinetics and thermal properties of 2-PZ/PGMA/epoxy resin system are also investigated using differential scanning calorimeter, Fourier transform infrared spectrometer, and thermogravimetric analysis. Results show that 2-PZ/PGMA has good sphericity and narrow diameter distribution. The curing process of the 2-PZ/PGMA/epoxy resin system contains autocatalytic mechanism. Compared with that of pure epoxy, the presence of the 2-PZ/PGMA has little effect on thermal stability for the epoxy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Intrinsically adhesive and temperature tolerant flexible sensors are fabricated. • Strain sensor achieves a GF of 2.58 and a sensing range of 0–1000%. • Reliefs on electrodes lead to a GF of 2.14 kPa−1 for pressure sensor. • Wireless strain sensor is demonstrated based on a bluetooth protocol. Hydrogel-based flexible sensors are of promising applications in various fields, but fabrication of such sensors with integrated high performances remains a challenge. In this work, flexible sensors (both strain sensors and pressure sensors) with integrated high performances are fabricated utilizing double network (DN) organohydrogels. Because of the unique structure of DN organohydrogels, the flexible sensors exhibit intrinsic adhesion without introducing components that are often used to obtain adhesive hydrogels, such as polydopamine, nucleobases or proteins. In addition, outstanding temperature tolerance (−18 to 80 °C), high stretchability (>2000%), tensile strength (>300 kPa), self-healing ability (96.5%) and transparency (90%) are also achieved. Resistive-type strain sensors of DN organohydrogels achieve high gauge factor (GF = 2.58), low response time (0.18 s), large sensing range (0–1000%) and reversible sensing ability (>1000 cycles). Sandwich-shaped capacitive-type pressure sensors comprising DN organohydrogel electrodes with reliefs exhibit a high sensitivity of 2.14 kPa−1. Such flexible sensors can be applied in monitoring various human motions and subtle physiological activities and further promoted as wireless sensors on the basis of a Bluetooth protocol. [ABSTRACT FROM AUTHOR]