Extended Data Fig. 6: Actuation performance experiments of VHB and SBAS.
a, b, The circular actuators of VHB (a) and SBAS (b) are composed of two DE membranes (thickness 1.5 mm) with pre-stretch of 3 × 3, fixed on a rigid ring. A carbon grease electrode is sandwiched by the two DE membranes with an initial radius (R) of 1.25 cm as the active region. The carbon grease electrode is connected to the power source as the high-voltage end. The external water surrounding the other sides of the DE membranes is connected to the power source as the ground end. When a high voltage is applied, the active region expands to the actuated radius of r. The area strain is calculated as (r2 − R2)/R2. c, The experimental set-ups for the performance test of the DE actuator. The circular actuators are installed in a pressure chamber and connected to an external high-voltage power source (Trek 610E). The voltage-induced area strain of the DE circular actuator is recorded from the top by a camera protected by a metallic vessel. With an identical actuating voltage of 8 kV at 1 Hz, we tested the actuation performances of VHB and SBAS under various temperatures (2.7 °C, 5.0 °C, 10.0 °C, 15.0 °C, 20.0 °C and 25.0 °C) and hydrostatic pressures (0 MPa, 25 MPa, 50 MPa, 75 MPa, 100 MPa and 110 MPa). d, The SBAS film (thickness of 1.5 mm) after solution casting and solvent evaporation process (320 g SBAS is dissolved in 3,000 ml tetrahydrofuran; the casting area is 1 m × 1 m). e, AFM phase image of the SBAS film (the bright islands indicate polystyrene nanodomains with high stiffness). f, The schematic shows that owing to the thermodynamic incompatibility of different blocks, the physically crosslinked SBAS elastomer has a sea–island microstructure via microphase separation of polystyrene blocks (blue) and poly(butyl acrylate) (orange). g, GPC curves of molecular weight distribution indicate the block-by-block chain extension process (black, then red, and finally the blue curve) during the synthesis of the triblock coploymer SBAS. PSt, polystyrene; PnBA, poly(n-butyl acrylate). h, Dynamic mechanical analysis of VHB (red) and SBAS (black). The glass transition temperature of the material can be determined from the tipping points on the curve of storage modulus versus temperature. SBAS material has a lower Tg (−17.2 °C) than VHB (0.3 °C). The blue dashed line indicates the temperature close to the Mariana Trench (2.7 °C). At this temperature, the VHB is close to its glass transition and has higher storage modulus than SBAS, resulting in its reduced actuation in low temperature and high pressure (Fig. 3d).
