The Electrorheological Effect for Polyhedral Silsesquioxane Cage Structures with Cyanopropyl Functional Groups

Previous research has shown that sulfonated polyhedral silsesquioxane (s-POSS) material when mixed with silicone oil (PDMS) exhibits a significant ER effect. Here we show that cyanopropyl POSS (c-POSS) particles in silicone oil also show significant ER activity. The effects of the functional group attached to the nanocages (POSS) on the rheological properties of the suspension is demonstrated through steady flow and oscillatory tests. Furthermore the electrorheological properties of these mixtures is also shown in these tests. The yield stress, t_y, scales with the electric field, E, as τ_y ~ E^1.15. The elastic storage modulus of the suspension at small strains (γ=0.10) scales with the electric field E as G’ ~ E^0.99-1.76. The research also contributed answers to the effects of changing the concentration of c-POSS particles. The preyield, yield and postyield characteristics of the ER fluid were determined using the flow curves, small amplitude oscillatory tests, and thixotropic stress loop tests.