title: Rheological properties and formation mechanism of DC electric fields induced konjac glucomannan-tungsten gels.
abstract: 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, WO4(2-) 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 and development of KGM gels as well as polysaccharide gels.
authors.affiliation: Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Materials, Xiamen University, Xiamen, Fujian 361005, China; School of Biological Science and Biotechnology, Minnan Normal University, Zhangzhou, Fujian 363000, China.
authors.forename: Lixia
authors.initials: L
authors.lastname: Wang
authors.affiliation: Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Materials, Xiamen University, Xiamen, Fujian 361005, China.
authors.forename: Yaoping
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Materials, Xiamen University, Xiamen, Fujian 361005, China.
authors.forename: Youhui
authors.initials: Y
authors.lastname: Lin
authors.affiliation: College of Food Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China. Electronic address: pang3721941@163.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Pang
authors.affiliation: Department of Physics, National University of Singapore, Block S12, 2 Science Drive 3, 117551, Singapore; Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Materials, Xiamen University, Xiamen, Fujian 361005, China. Electronic address: phyliuxy@nus.edu.sg.
authors.forename: Xiang Yang
authors.initials: XY
authors.lastname: Liu
mesh_terms: D031056:Amorphophallus / Q000737:chemistry*; D002240:Carbohydrate Sequence; D055119:Elastic Modulus; D004548:Elasticity; D004560:Electricity; D020100:Hydrogels / Q000737:chemistry*; D008351:Mannans / Q000737:chemistry*; D014414:Tungsten / Q000737:chemistry*; D014783:Viscosity
chemical_list: D020100:Hydrogels; D008351:Mannans; C022901:(1-6)-alpha-glucomannan; D014414:Tungsten
keywords: DC electric fields; Electrogel; Formation mechanism; Konjac glucomannan; Rheological properties