Electromechanical properties study of 1-butyl-3-methylimidazolium chloride/cellulosic gel blended with polydiphenylamine

1-Butyl-3-methylimidazolium chloride (BMIMCl) is an ionic liquid utilized as an effective cellulose gelling agent for the fabrication of electro-responsive cellulose. The cellulose electromechanical properties are primarily dependent on the ionic polarization of BMIM+ and its mobility. This work focuses on the synergism between the ionic contribution of ionic liquid/cellulosic gel (CelGel) and the electronic contribution of a conductive polymer, polydiphenylamine (PDPA) of various doping levels and concentrations (%v/v) under electrical actuation. Initially, CelGel is blended with doped PDPA of various doping levels. At 2.50%v/v, the CelGel blend exhibits the highest electrical conductivity of 21 S/cm at a 10:1 PDPA doping level. This results from proton conduction and electron delocalization which are intrinsically present within the doped PDPA embedded in the blends. Higher PDPA doping level in the blends produces lower storage modulus sensitivity. This suggests that the higher doping levels of PDPA create a higher degree of short-range ionic polarization, thus retarding BMIM+ mobility and lowering storage modulus sensitivity. The %v/v of undoped PDPA (uPDPA) in the blends is further investigated with a %v/v variation between 0.01%v/v and 7.50%v/v. A larger amount of uPDPA in the blend provides a larger electrostatic binding interaction between BMIM+ and Cl− counterion, and this diminishes the storage modulus sensitivity as well. With a higher amount of uPDPA added, the bending angle also diminishes due to the electrostatic binding interaction. However, the optimal %v/v of uPDPA is 0.01%v/v, the ionic-electronic synergism produces the highest non-symmetric swinging angle of 77° accompanied with dielectrophoresis and electrophoresis force of 8.25 mN. This condition allows a number of polarizable domains on uPDPA with less rigidity on the CelGel relative to the pristine CelGel. The results suggest that uPDPA is a potential conductive polymer candidate for producing tailor-made electromechanical responses at optimal %v/v in the categories of ionic gels and dielectric elastomers.