Jinchun Li

Hydrogels based on Schiff base chemistry are widely used for in situ applications due to their rapid gelation property. However, the inherent hydrolytic instability and dynamic nature of imine bonds limit their use in scenarios requiring long-term structural stability and stress relaxation resistance, especially in non-neutral pH environments. Herein, we report an imine hydrogel with a stable cross-linked network that exhibits enhanced resistance to hydrolysis. The hydrogel forms rapidly (2) generated by the deprotonation of -NH₃⁺ groups on poly(allylamine hydrochloride) (PAH). Multipoint cross-linking between PAH and GA not only facilitates the rapid gelation process at low pH value but also imparts a robust and resilient network, enabling exceptional hydrolytic stability even under strongly acidic conditions. Based on these properties, the hydrogel can be employed as a stable acidic polyelectrolyte in the domains of signal sensing and energy storage. With moderate incorporation of LiBF₄, the hydrogel can be used to fabricate antifreezing sensors for real-time monitoring of laryngeal activity or finger movements. Furthermore, the rapid gelation kinetics facilitate in situ assembly of flexible supercapacitors within 15 min, which maintain practical and stable energy storage properties after 1 h of gelation. The resulting supercapacitors demonstrate high specific capacitance (124.1 F g^-1), an energy density (E) of 17.1 Wh kg^-1, and stable interfacial contact during deformation, with ideal cycling stability of over 5000 charge-discharge cycles without packaging. This work provides a strategy for rapid preparation of stable hydrated imine polymers, particularly suitable for field-based in situ fabrication of polyelectrolytes for electronic and energy storage devices.

Developing bio‐based plasticizers not only aids in the reduction of fossil fuel consumption but also presents a lower risk to human health. In this study, a fully biodegradable plasticizer—levulinate malate ethanol lactates (LMEL) was successfully synthesized from L‐lactic acid, DL‐malic acid, levulinic acid, and ethanol, and was compared with commercially plasticizers (acetyl tributyl citrate (ATBC), dioctyl phthalate (DOP) and di‐2‐ethylhexyl terephthalate (DOTP)). 40 phr LMEL plasticized polyvinyl chloride (PVC) (40LMEL) yielded a remarkable elongation at break of 526.9%, compared with the pure PVC resin (4.5%), thereby significantly enhancing the flexibility of PVC. Moreover, the optical transparency of 40LMEL samples was found to be equivalent to PVC plasticized with three commercial plasticizers. Most importantly, compared with three commercial plasticizers, 40LMEL exhibited superior resistance to migration and volatility, with mass losses of 1.055% in H₂O, 13.601% in n‐hexane, 14.636% in ethanol, and 1.496% in activated carbon, respectively. Soil degradation experiments have demonstrated that LMEL can be broken down by microorganisms in the soil into nontoxic aliphatic compounds (e.g., 4‐oxo‐pentanoic acid, and 4,5,7‐trihydroxy 2‐octenoic acid, et al.). Collectively, LMEL exhibited better overall performance than three commercial plasticizers. This work provides new options for the design of efficient fully bio‐based plasticizers.

Enhancing the flame retardancy of electrolytes and the stability of lithium anodes is of great significance to improve the safety performance of lithium–sulfur (Li–S) batteries.