Ion-Containing Bottlebrush Elastomers as Pressure-Sensitive Electroadhesives

Abstract: This study presents a materials-design framework for low-voltage pressure-sensitive electroadhesives based on ion-containing bottlebrush polymers that combine the on-demand reversibility of traditional electroadhesives with the tunable conformability typical of pressure-sensitive adhesives (PSAs). Two complementary bottlebrush polymers bearing pendant flexible side chains and independently tunable anionic or cationic groups were designed to form soft and tough elastomers after crosslinking. When the two oppositely charged bottlebrush networks were brought into contact, a smooth, continuous interface formed, which is locally charge neutral due to the presence of mobile counterions. At low voltages (less than 2 V), mobile ions migrate toward the electrodes, creating an interfacial heterojunction and significant electrostatic attraction that enhances adhesion, yielding an on/off ratio of up to more than 4.5. The low-voltage operation and PSA-like mechanics of bottlebrush electroadhesives, even at charge density as low as 18 C/g, create opportunities in applications such as soft robots, haptic devices, and biomedical devices.