Rheological properties and formation mechanism of DC electric fields induced konjac glucomannan-tungsten gels

•Rational design of molecular and polymetric gelators is an elusive and herculean task, despite the rapidly growing body of literature devoted to such gels over the past several decades. So far, a variety of external physical stimuli (e.g. light and ultrasound) have been used to switch molecular assembly involved in the gel formation.•However, to our best knowledge, the research on using electric field to induce polysaccharide self-assemble to form gel has not been reported. In this paper, DC electric field was successfully applied to induce the formation of konjac glucomannan (KGM) gel, a new type of thermal-stable gel, in the presence of sodium tungstate.•The possible mechanism of gel formation and rheological properties have been discussed. Unlike traditional ways of preparing KGM gels, our approach didn’t require the addition of any alkali, borax, or other gums.•This type of gel overcomes the problems currently faced due to the poor thermal-stability of KGM gels as well as the problems often faced while preparing gels in alkaline condition.•Our finding may pave the way to use DC electric fields for the design and development of KGM gels and to apply KGM gels for practical applications. Konjac glucomannan-tungsten (KGM-T) hydrogel of electrochemical reversibility was successfully produced under DC electric fields in the presence of sodium tungstate. The structure and the effects of sodium tungstate concentration, KGM concentration, voltage and electric processing time on the rheological properties of the gels were investigated. pH experiments showed that KGM sol containing Na2WO4·2H2O in the vicinity of the positive electrode became acidic and the negative electrode basic after the application of DC electric fields. Under acid conditions, WO42− ions transformed into isopoly-tungstic acid ions. FTIR and Raman studies indicated that isopoly-tungstic acid ions absorbed on KGM molecular chain and cross-linked with OH groups at C-6 position on sugar units of KGM. Frequency sweep data showed with increasing sodium tungstate concentration, voltage, and electric processing time, the viscoelastic moduli, i.e., the storage and the loss moduli of the gel increased, whereas an increase in KGM concentration led to a decrease in gel viscoelastic moduli. The temperature sweep measurements indicated the obtained gel exhibited high thermal stability. Finally, the mechanism of gel formation was proposed. Our work may pave the way to use DC electric fields for the design