Lyophobic heterogeneous systems (LHS) are made of mesoporous materials immersed in a non-wetting liquid. One application of LHS is the nonlinear damping of high frequency vibrations. The behaviour of LHS is characterized by P - ΔV cycles, where P is the pressure applied to the system, and ΔV its volume change due to the intrusion of the liquid into the pores of the material, or its extrusion out of the pores. Very few dynamic studies of LHS have been performed until now. We describe here a new apparatus that allows us to carry out dynamic intrusion/extrusion cycles with various liquid/porous material systems, controlling the temperature from ambient to 120 °C and the frequency from 0.01 to 20 Hz. We show that for two LHS: water/MTS and Galinstan/CPG, the energy dissipated during one cycle depends very weakly on the cycle frequency, in strong contrast to conventional dampers.

Electroadhesion is a phenomenon ruled by many characteristic intrinsic parameters. To achieve a good adhesion, efficient and durable, a particular attention must be provided to the adhesion forces between the involved parts. In addition to the size and geometry of electrodes, parameters of materials such as dielectric constant, breakdown electric field, and Young’s modulus are key factors in the evaluation of electroadhesion efficiency for electrostrictive polymers and electroactive devices. By analyzing these material parameters, a method is proposed to justify the choice of polymer matrices that are fit to specific electroadhesion applications. Another purpose of this work aims to demonstrate a possibility of accurately measuring the electroadhesion force. This physical parameter has been usually estimated through equations instead, because of the complexity in setup implementation to achieve highly precise measure. Comparisons based on the parameters criterion reveal that besides the intrinsic properties of material, some other parameters relating to its physical phenomena (e.g., saturation of dipolar orientation under high electric field leads to decrease dielectric constant), or physical behavior of the system (i.e., surface roughness reduces the active electrode area) must be thoroughly considered. Experimental results pointed out that plasticized terpolymer leads boosted electroadhesion performance compared to the other counterparts, up to 100 times higher than conventional polymers. The developed materials show high potential in applications of active displacement control for electrostrictive actuation.

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