Abstract
Elastic materials with increased permittivity (epsilon') were obtained in a three-step process starting from a hydroxyl end-functionalized polydimethylsiloxane (PDMS) of a high molecular weight (M-w = 139 kDa), trimethylsilyl end-blocked silicones that carry hydrosilane, cyanopropyl and hexyl groups P-x (where x represents the mol% of cyanopropyl groups), and tetraethoxysilane (TEOS). The hydrosilane groups of P-x were first hydrolyzed and the formed hydroxyl groups were subsequently reacted with partially hydrolyzed TEOS and further used as high epsilon' components, cross-linkers, and reinforcing agents for the PDMS matrix. A high wt% of the polar component P-x was incorporated into the nonpolar PDMS matrix by forming interconnected networks. Thermal (DSC, DMA) and morphological investigations (SEM) show the biphasic morphology of the networks. The dielectric, mechanical, and electromechanical properties of the films were investigated. Materials with good elastic properties, increased epsilon', and a high breakdown field (E-b) were obtained. The best material has an elastic modulus of 800 kPa at 10% strain, an epsilon' = 4.5, and a maximum actuation strain of 8% at E-b - 56 V mu m(-1).