Enhanced Stimuli-Responsive Electrorheological Property of Poly(ionic liquid)s-Capsulated Polyaniline Particles

Abstract

Abstract:We used inherently conducting polyaniline as a core to develop a type of poly(ionic liquid)s-capsulated polyaniline composite particles in order to both overcome the surface charged character of pure poly(ionic liquid)s particles prepared by post ion-exchange procedure, and enhance electrorheological (ER) effect. The structure was characterized by different techniques and the electrorheological suspension was prepared by dispersing the composite particles in silicone oil. Under electric fields, the electrorheological properties of the suspensions of poly(ionic liquid)s-capsulated polyaniline composite particles were measured and compared with their single forms. It is demonstrated that the composite particles have distinctly enhanced electrorheological effect compared with the pure poly(ionic liquid)s and polyaniline particles under electric stimuli. At 4 kV/mm of electric field, the yield stress of the suspension of poly(ionic liquid)s-capsulated polyaniline composite particles in silicone oil is about 2.3 kPa, which is twice as high as 1.2 kPa stress of the suspension of poly(ionic liquid) particles and 2.5 times as high as 0.9 kPa stress of the suspension of polyaniline particles. By using dielectric spectroscopy, microscopic observation, and oscillation rheology, we studied the origin of this enhanced electrorheological effect. The results indicated that wrapping polyaniline into poly(ionic liquid)s could partly suppress the positively charged surface state of poly(ionic liquid)s particles prepared by post ion-exchange procedure and improve the column-like electrorheological structure. This suppression should be responsible for the enhanced electrorheological effect of poly(ionic liquid)s-capsulated polyaniline composite particles.

The Effect of Dielectric Polarization Rate Difference of Filler and Matrix on the Electrorheological Responses of Poly(ionic liquid)/Polyaniline Composite Particles

“…The phosphorus tends to distribute on the edge of particles, which indicates the unsymmetrical structure by the post ion-exchange procedure. This can be confirmed with our previous work, in which we proved the PIL/PANI structure by comparing the electrical response with PANI/PIL mixture [38]. However, it is still difficult to distinguish the distribution of PANI due to that both PIL and PANI have nitrogen element.…”

“…While for PIL/PANI, the columns seem to be more uniform except Figure 4D. This phenomenon has been discussed in our previous work in detail, so that is not repeated any more in this study [38]. Figure 5 shows the variation of shear stress with shear rate for the PIL/PANI ER fluids at different electric fields.…”

“…In addition, we note that the total value of ∆ε' of the ER fluid of PIL/PANI is not much larger than that of the ER fluid of neat PIL, which is not enough to explain the enhanced yield stress. This enhancement due to the improvement of ER structure has been investigated in our previous work, and, therefore, is not discussed here [38]. Compared to other PIL-based composite, like GO/PPy/PIL composite nanosheets or PIL/SiO 2 composite particles [29,30], the ∆ε' of PIL/PANI(NH 3 ) composites is also relatively larger and λ is more suitable and thus result in enhanced ER response compared to them.…”

“…PIL/PANI composite particles were prepared by the modified method of Marcilla et al [37]. The preparation details of P[VBTMA][PF 6 ] particles and P[VBTMA][PF 6 ]/PANI composite particles refer to our previous work [38]. The difference is that a spot of HCl was added into the reaction system to dissolve aniline at the outset.…”

Enhanced Electrorheological Response of Cellulose: A Double Effect of Modification by Urea-Terminated Silane

“…Electrorheological (ER) fluids are a form of smart colloidal suspensions, whose rheological properties will change significantly upon the application of an electric field [32,33,34]. The ER fluids consist of dielectric or semiconducting particles as the dispersed phase and insulating liquids as the continuous phase.…”