In-Situ Swelling-Gated Chemical Sensing Actuator

Abstract

Stimuli-responsive elastic organogels have a potential for functional sensors and actuators. However, it remains a challenge to prepare an organogel actuator that can be driven by in-situ swelling to generate controlled shape morphing and maintain its kinematic activities even having been saturated with organic solvents. We herein report a robust elastic organogel that is synthesized through ring-opening polymerization of a long chain epoxide monomer into a crosslinking fluoro-network (CFN). The structure results in the organogel being capable of absorbing polar organic solvents (maximum swellability: 178±10%) and generating indefatigable shape morphing, even in a solvent-saturated state. The CFN organogel is resistant to strong acid/alkali solutions (treating with 2M HCl and NaOH at 60 °C for 20 h), and high temperatures (heating at 250 °C for 5 min) without losing its responsiveness to organic solvents. It is also stretchable (strain, 130%), robust (stress, 7.0 MPa), and elastic, and can keep these properties after treatment in harsh conditions. Importantly, the CFN organogel is capable of in-situ swelling (no diffusion) by organic droplets to induce shape morphing in a controllable manner, which is devoid of the assistance of any structural designs such as surface patterning, bilayer structures and origamis. The single-layered CFN organogel deforms from two- to three-dimensional geometries only through the in-situ swelling of organic droplets at appropriate positions over the organogel surface. A series of kinematics tests demonstrate that the CFN organogel has a potential for chemical sensing devices.