Abstract
Ionogels offer huge potential for a number of applications including wearable electronics and soft sensors. However, their synthesis has been limited and often relies on non-renewable or non-biocompatible components. Here we present a novel two-component ionogel made using just deep eutectic solvents (DESs) and cellulose. DESs offer a non-volatile alternative to hydrogels with highly tuneable properties including conductivity and solvation of compounds with widely varying hydrophobicity. DESs can be easily made from cheap, biodegradable and biocompatible components. This research presents the characterisation of a series of soft conductive gels made from deep eutectic solvents (DESs), specifically choline chloride-urea and choline chloride-glycerol, with the sole addition of TEMPO-oxidised cellulose nanofibrils (OCNF). A more liquid-like rather than gel-like conductive material could be made by using the DES betaine–glycerol. OCNF are prepared from sustainable sources, and are non-toxic, and mild on the skin, forming gels without the need for surfactants or other gelling agents. These DES-OCNF gels are shear thinning with conductivities up to 1.7 mS cm−1 at ∼26 °C. Given the thousands of possible DESs, this system offers unmatched tunability and customisation for properties such as viscosity, conductivity, and yield behaviour.
Highlights
Conductive gels offer promising applications e.g. as so sensors, in energy storage, and wearable electronics.[1,2,3,4,5] Hydrogels with ionic species have some potential in this area
All three of the chosen deep eutectic solvents (DESs), choline chloride–urea (ChCl–U), choline chloride–glycerol (ChCl–Gly), and betaine–glycerol, are viscous liquids on their own, but addition of oxidised cellulose nanofibrils (OCNF) to any of them resulted in immediate thickening
In the case of ChCl–Gly and Choline chloride– urea (ChCl–U), self-standing physical gels formed with OCNF a er water removal by freeze-drying
Summary
Conductive gels offer promising applications e.g. as so sensors, in energy storage, and wearable electronics.[1,2,3,4,5] Hydrogels with ionic species have some potential in this area. Some works have used deep eutectic solvents as plasticisers for starch or cellulose to create conductive lms with improved mechanical properties.[20,21,22] Others have used DESs as polymerisation media, e.g. of 2-hydroxyethyl methacrylate[23,24] or poly(ethylene glycol) diacrylate,[25] to obtain eutectogels. Choline chloride–glycerol (ChCl–Gly) was synthesised by combining choline chloride and glycerol in a 1 : 2 mol ratio All these DESs were stirred at 50 C to form a homogenous liquid and placed in a freeze-dryer to remove any residual water.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
