Preparation of guar gum-based functional materials using ionic liquid

Abstract

This paper reports the facile preparation of gels of guar gum (GG) with an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl), from the solutions of GG in BMIMCl in various concentrations by heating–cooling process. The mechanical properties of the gels were evaluated by stress–strain curves under both compressive and tensile modes. Furthermore, the GG/BMIMCl gels were converted into films by compression technique (60 °C, 4 MPa), followed by soaking in ethanol. The mechanical properties of the resulting films depended on the contents of GG in the films. The film became hard upon heating and returned back to soft nature upon cooling (temperature-induced shaping ability). The TGA and XRD analyses of the film indicated that this property was caused by construction and disruption of crystalline structures of GG in the film by evaporation and absorption of water during the heating–cooling process. The GG/BMIMCl gel was also converted into xerogels by soaking it in ethanol and water, followed by lyophilization.