Electrorheological (ER) elastomer is an alternative of ER fluid by replacing the liquid continuous phase with elastic solid, and both are electro-responsive intelligent soft materials. ER elastomer is composed of dielectric particles dispersed in polymer elastomer and confined in the polymer matrix during curing process. Under the electric field, the particles are polarized and attract each other by electrostatic force, and the ER elastomer exhibits improved elastic modulus and damping characteristics, which can be applied in intelligent shock absorption and artificial muscles. Polyurethane (PU) is composed of thermodynamically incompatible soft segment domain and hard segment domain. Due to the inhomogeneity of microstructures, PU has good tensile resistance. The chain structure and modulus of PU can be adjusted by changing the composition of the soft and hard segments. For typical ER elastomers, polydimethylsiloxane (PDMS) is applied as the matrix due to its simple preparation process and low dielectric constant; however, the dielectric constant of PU is higher and related to its structure. According to the traditional ER polarization theory, the significant dielectric constant difference between dispersed particles and matrix is conducive to preparing high-performance ER materials. In order to reduce the dielectric constant of PU, we used PDMS with different molecular weight (Mw=1000, 2000, and 3000) as the soft segment of PU to adjusted the dielectric constant of PU. The experimental result showed that the dielectric constant of the matrix elastomer decreases with Mw of the PDMS. The ER efficiency of PU-based ER elastomers at 3.0 kV/mm electric field strength was 280%, 190%, and 144%, respectively, which also decreased with the Mw of PDMS.

PU,ER elastomer,ER efficiency,dielectric constant