Integrated Design and Synthesis of Soft Matrices with High Permittivity

Emerging applications, such as dielectric elastomer actuators (DEAs), haptics, and bioelectronics, would benefit from soft matrices that simultaneously exhibit high permittivity (relative permittivity <i>ε_r</i> ≥ 10) and low elastic moduli (<i>E</i> ≤ 1 MPa). For example, the energy density of DEAs depends on <i>ε_r</i>², while their actuation strain scales with <i>ε_r</i>. However, most soft elastomers and gels that serve as compliant dielectric layers exhibit low permittivity (<i>ε_r</i> ≤ 10). Consequently, the operation of DEAs requires kilovolt-scale potentials to achieve targeted actuation strains and energy densities. The incorporation of high-<i>ε_r</i> fillers affords little improvement, since liquid fillers (<i>e.g.</i>, liquid metals) decrease breakdown strength, while solid fillers (<i>i.e.</i>, strontium titanate particles) increase modulus. In this talk, we will describe recent advances to design and synthesize intrinsically polarizable elastomers and gels based on a library of small molecules with a large dipole moment and a low melting point – each of which exhibits exceptional permittivity (<i>ε_r</i> ≥ 250) in the low frequency limit. Their synthesis is both facile (3-5 synthetic steps) and scalable (up to 250 g) from inexpensive starting materials. Using this library, we have created elastomers and gels with <i>ε_r</i> ≥ 100 and <i>E</i> &lt; 1 MPa, which may find potential application in high-strain and energy-dense DEA, haptic, and bioelectronic-based devices.