Design and preparation of bio-based dielectric elastomer with polar and plasticized side chains

A new dielectric elastomer with large actuated strain driven by low electric field was synthesized from di-n-butyl itaconate and isoprene through free radical redox emulsion polymerization. The effect of the copolymerized proportion of poly(di-n-butyl itaconate-co-isoprene) (PDBII) and the dosage of crosslinking agent on the elastic modulus, dielectric properties, and actuated strain of the elastomer were investigated, and a potential dielectric elastomer candidate containing 70 wt% di-n-butyl itaconate was obtained. The permittivity of the PDBII crosslinked by 3.0 phr of dicumyl peroxide was 5.68 at 10³ Hz, which was higher than that of commercial acrylic and silicone dielectric elastomers. Without any prestrain, an actuated strain of 20% was obtained at an electric field of 30 kV mm^-1. In order to further increase the actuated strain, barium titanate (BaTiO₃), a high-dielectric-constant ceramic powder, was utilized to fill the PDBII to form a BaTiO₃/PDBII composite. The dielectric constant of the composite increased with increasing content of BaTiO₃, and the elastic modulus of the composite was lower than that of the unfilled PDBII, leading to a larger dielectric actuated strain of the composite.