Electric-Field Regulation of Adhesion/De-Adhesion/Release Capacity of Transparent and Electrochromic Adhesive

Removing adhesive nondestructively and intact from the adhered surface is a difficult challenge for advanced adhesive materials. Compared with the commonly used thermal or chemical release, the controlled adhesive release via electric-field offers practical application advantages. However, a noninvasive release mode such as this has not been available for the de-bonding of supramolecular adhesives that originate from small organic molecules. Herein, a conductive hydrogel with surface adhesion and electric field-triggered de-adhesion and release is fabricated from thioctic acid (TA) and L-arginine (LA). The non-covalent intermolecular attractions of poly[TA-LA], especially its electrostatic interactions, not only endow it with useful bulk-state properties and strong adhesion (up to 363.3 kPa) but also generate electric responsiveness for on-demand de-adhesion and release. The poly[TA-LA] adhesive layer can be easily released within a short time (<60 s) under a mild voltage (5≈10 V). After a combined experimental and theoretical investigation, It is concluded that the adhesive-layer morphological and mechanical changes, activated by a weak current (1.1≈3.2 mA), are responsible for the adhesion failure, which takes place primarily at the anode. Importantly, rapid electric release of poly[TA-LA] is applicable at low temperatures (5 V, 60 s, -40 °C) or underwater (5 V, 60 s, 25 °C).