Bonding of Acrylic Pressure‐Sensitive Adhesives and Silicone Elastomers via Surfactant‐Assisted Plasma Activation for Soft Robotics

ABSTRACT Acrylic pressure‐sensitive adhesives (PSAs) and silicone elastomers are widely used in soft robotics; however, robust bonding between these dissimilar soft materials remains challenging without primers or stiff intermediate layers that compromise compliance. Because these materials provide complementary mechanical and functional properties, reliable integration is essential for expanding soft robot design freedom. Herein, a simple bonding method is presented that eliminates primers and stiff intermediate layers by combining oxygen‐plasma activation of the PSA with surfactant‐assisted interfacial activation of uncured silicone during curing. This approach enables strong bonding while preserving material compliance. The resulting interface achieves an adhesion strength of 0.4 N/mm, approximately fivefold higher than that of the control, while optimization of the surfactant concentration and plasma conditions increases it to 0.5 N/mm. Further optimization of curing conditions increases the adhesion strength to 1.61 N/mm, corresponding to an approximately twentyfold improvement over the control. The bonded interface retains over 90% of its adhesion strength after 72 h under both ambient storage and water immersion. Mechanical characterization confirms that the intrinsic compliance of the PSA and silicone elastomer is largely preserved. The applicability of the method is demonstrated using an electrically driven jellyfish robot that achieves underwater swimming at 2.5 mm/s.