Electrorheology of suspensions of poly(ethylene glycol)/poly(vinyl acetate) blend particles

We prepared poly(ethylene glycol) (PEG)/poly(vinyl acetate) (PVAc) blend particles and studied the electrorheological (ER) effect of their suspensions. When a dc electric field is applied to the neat PVAc suspension, the particles aggregate to the negative electrode and does not show the ER. But the suspension of blend particles with PEG/PVAc = 60/40 shows a little higher yield stress than neat PEG. Furthermore, the ER effect does not disappear in the PVAc rich blend, even at PEG/PVAc = 5/95. In addition, the enhancement of ER effect by PVAc is not observed in neat component particle mixtures. From the observation of chain structures between electrodes by a microscope, the PEG rich blend particles form more concentrated chains compared with neat PEG. The number of chains in the system is decreased and the thickness of each chain is increased in PVAc rich blend.