Enhanced Electromechanical Properties of Three‐Phased Polydimethylsiloxane Nanocomposites via Surface Encapsulation of Barium Titanate and Multiwalled Carbon Nanotube with Polydopamine

Owing to its low modulus, high breakdown strength, and low dielectric loss, polydimethylsiloxane (PDMS) is used as a great dielectric elastomer despite its low dielectric permittivity. Herein, polydopamine (PDA) is used to encapsulate barium titanate (BT) and multiwalled carbon nanotube (MWCNT) in situ during its polymerization to prepare core–shell structured fillers, which are then solution‐compounded with PDMS, and subsequently vulcanized with a cross‐linking agent. The resulting three‐phased nanocomposites exhibit improved filler‐PDMS interactions upon filler PDA‐encapsulation likely due to interfacial hydrogen bonding, thereby to enhance filler dispersion within the PDMS matrix. Compared with the unencapsulated PDMS nanocomposites, a softening effect (i.e., decreased cross‐linking) by the finer filler‐dispersion, in the context of a hardening effect by filler network formation, strengthens in the PDA‐modified nanocomposites to produce their lower moduli. Additionally, the insulating, interfacial PDA partially inhibits the formation of conductive paths and leakage currents, causing decreased dielectric loss while increased breakdown strength of the nanocomposites. Therefore, the PDA‐encapsulated BT and MWCNT filled PDMS nanocomposites display excellent electromechanical properties with a largest possible actuated strain of 7.0% at a breakdown strength of 13.9 kV mm−1, which is 1.8 times that (3.9%@15.0 kV mm−1) of their unencapsulated counterparts and 4.7 times that (1.5%@18.4 kV mm−1) of unfilled, neat PDMS. Core‐shelled particles with BaTiO3 and MWCNT as the core and polydopamine as the shell are prepared and then compounded with polydimethylsiloxane. The vulcanized, three‐phased nanocomposites exhibit a large actuated strain of 7.0% (@13.9 kV mm−1), which is 1.8 times that of its unencapsulated counterparts (3.9%@ 15.0 kV mm−1) and 4.7 times that of neat PDMS (1.5%@18.4 kV mm−1).