We report a novel tough self‐healing electrolyte on the basis of poly (acrylic acid‐co‐acrylamide) cross‐linked by divalent cobalt ions (Co2+) (P(AA‐co‐AAm)/CoCl2). Intermolecular and intramolecular hydrogen bonding work together with the metal‐coordination between Co2+ and carboxylic ions to form a hydrogel, which can resist various deformations. The hydrogel electrolyte exhibits excellent mechanical performance (elongation at break >1200 %, compressive stress >600 kPa and compressibility >90 %). The established supercapacitor based on P(AA‐co‐AAm)/CoCl2 can hold its capacitance even after bending, twisting, compressing and self‐healing. Moreover, it retains 90 % capacitance after 5000 cycles. Our electrolyte shows great prospects in manufacture of intelligent flexible equipment.
Chitosan can be widely used in many areas owing to its unique properties, although its poor solubility in water is still a limiting factor. In the present study, low molecular weight chitosan (LMWC) was prepared by degradation with NaClO so that chitosan was able to dissolve in water. Chitosan to liquor ratio, NaClO content, temperature, and time were considered variables of NaClO degradation, and the Box-Behnken design was used to determine optimal conditions. There was good agreement between the experimental data and their predicted counterparts. The optimum conditions for chitosan degradation were estimated to be 1:67.91 of chitosan to liquor ratio, 22.03% of NaClO content, a temperature of 90.3 °C, and a time of 3.07 h. It was found that synthesis under these optimized conditions achieved the lowest molecular weight (10,937.4 Daltons). In addition, Fourier transform infrared spectroscopy, X-ray diffractograms, and thermogravimetric analysis showed that the structure of LMWC was similar to the original chitosan, while the crystallinity and thermal stability decreased after degradation.
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