Enhancement of the actuation performance of dielectric triblock copolymers modified with additives

Abstract

To enhance actuation performance without prestrain, an elastomeric acrylic triblock copolymer, poly(methyl methacrylate)block-poly(n-butyl acrylate)-block-poly(methyl methacrylate), was modified with two kinds of additives, oligomeric poly(n-butyl acrylate) and the plasticizer dibutyl sebacate. An actuator modified with those additives showed about 6% strain, whereas the unmodified actuator showed only 1% strain for the same applied electric field without prestrain. In addition, actuation was attained at lower critical electric field strength (625 and 1000 V mm −1 for modified and unmodified actuators, respectively). Upon increasing the amounts of the additives, the electrically induced actuation velocity and degree of deformation increased. These results are explained by the dielectric and mechanical properties of the elastomers. The dielectric constants for elastomers modified with dibutyl sebacate were larger than those for elastomers modified with oligomeric poly(n-butyl acrylate). The initial tensile stresses of both of the modified elastomers were much smaller than that of unmodified elastomer. The results provide a route to enhancing actuation performance of dielectric elastomers without prestrain.

Artificial Muscles: Dielectric Elastomers Responsive to Low Voltages

“…Low voltage actuators can be in principle achieved with soft elastomers. They can be prepared either by reducing the cross‐linking density, using plasticizers, synthesizing bimodal heterogeneous networks, or incorporating bottlebrush segments into the polymer network . However, the dielectric breakdown of such soft elastomers is a hurdle still to be overcome .…”

Influence of Morphology and Rheological Properties on the Mechanical and Dielectric Behavior of Block Copolymer Gels

“…Jang and co‐workers demonstrated that HEX or BCC morphologies, with predominance of the softer block, present higher dielectric constants, in any frequency range studied, when compared to the LAM morphology, formed by alternating layers of the constituent blocks. In order to increase the predominance of the soft block, a strategy has been to prepare BCP physical gels, in which a large concentration of a low molecular weight compound selectively swells the soft block and the phase‐separated microdomains act as physical aggregates . Thus, in addition to increasing the dielectric constant, the gels allow the reduction of stiffness of the block copolymers, since the low molecular weight compound acts as a plasticizer in the system, achieving greater success for application as DEs.…”

“…When the reduction of the elastic modulus and the increase of the dielectric constant of these elastomers are achieved, they allow large deformations from an electric field . Among these, block copolymers (BCPs) have promising properties to be used as nanostructured dielectric elastomers …”

“…In order to increase the predominance of the soft block, a strategy has been to prepare BCP physical gels, in which a large concentration of a low molecular weight compound selectively swells the soft block and the phase‐separated microdomains act as physical aggregates . Thus, in addition to increasing the dielectric constant, the gels allow the reduction of stiffness of the block copolymers, since the low molecular weight compound acts as a plasticizer in the system, achieving greater success for application as DEs. Shankar et al and Kim et al used polystyrene‐ b ‐poly(ethylene‐ co ‐butylene)‐ b ‐polystyrene (SEBS) triblock copolymers with the addition of white mineral oil (MO), which interacts with the poly(ethylene‐butylene) midblock (PEB), to obtain gels of SEBS.…”

Enhanced electromechanical performance of bio-based gelatin/glycerin dielectric elastomer by cellulose nanocrystals

“…Silicones Liu, Liu, Zhang & Leng, 2009), acrylics (Jang, Hirai, Ueki & Kato, 2012;Kofod, Sommer-Larsen, Kornbluh & Pelrine, 2003;Pelrine, Kornbluh, Pei & Joseph, 2000) and polyurethanes (Mahapatra, Yadav, Yoo & Cho, 2011;Wongtimnoi, Guiffard, Bogner-Van de Moortèle, Seveyrat, Gauthier & Cavaillé, 2011) are the three most promising groups of DEs, which are all petroleum-based elastomers. To meet the growing demand of environmental protection and resource saving, it is imperative to explore bio-based elastomers as next-generation DE because the bio-based elastomers are available from biomass feedstock.…”