A novel one-pot strategy to construct 3D-printable cellulose nanofiber/poly(deep eutectic solvent) conductive elastomers

• Nanofibrillation, modification, polymerization are achieved in the same DES system. • LA (MA) in the DES system is polymerized into PDES with GMA. • CNF/PDES elastomers are formed with the chemical or physical cross-linking network. • CNF/PDES conductive elastomer has good mechanical properties. • CNF/PDES conductive elastomer can be applied for the 3D printed flexible sensors. A novel one-pot strategy is developed to construct the 3D-printable cellulose nanofiber/poly (deep eutectic solvent) (CNF/PDES) conductive elastomers. Specifically, the nanofibrillation and chemical modification of cellulose was achieved in the lactic acid/choline chloride (LA/ChCl) or maleic acid/choline chloride (MA/ChCl) deep eutectic solvent (DES) systems, whereby, the initial non-polymerizable DES (LA or MA/ChCl) system have the ability of in-situ polymerization is realized through the epoxide ring-opening reaction of glycidyl methacrylate (GMA) with LA (or MA). All the processes were completed in a one-pot DES system, and the preparation of CNF/PDES conductive elastomers were successfully realized. Both CNF/PDES conductive elastomers with chemical and physical cross-linking networks can be fabricated by this one-pot strategy. The self-aggregation of CNF and formation of double bonds effectively improved the mechanical properties of CNF/PDES conductive elastomer. The stress and strain of CNF/PDES composites increased from 59 to 330 KPa and 135 to about 300%, respectively, when the content of CNF reached 5 wt%. The feasibility of 3D-printable direct ink writing (DIW) of the CNF/PDES by UV light and their application in flexible sensors and human body monitoring were also discovered. The elaborate shape customized by DIW and UV curing realized complex signal detection and transmissions and showed excellent stability and sensitivity, thus promoted the application of nanocellulose in the field of flexible sensing.