Intrinsically Tuning the Electromechanical Properties of Elastomeric Dielectrics: A Chemistry Perspective

Abstract

Dielectric elastomers have the capability to be used as transducers for actuation and energy harvesting applications due to their excellent combination of large strain capability (100-400%), rapid response (10 s), high energy density (10-150 kJ m ), low noise, and lightweight nature. However, the dielectric properties of non-polar elastomers such as dielectric permittivity ε , breakdown strength E , and dielectric loss ε ″, need to be enhanced for real world applications. The introduction of polar groups or structures into dielectric elastomers through covalently bonding is an attractive approach to 'intrinsically' induce a permanent polarity to the elastomers, and can eliminate the poor post-processing issues and breakdown strength of extrinsically modified materials, which have often been prepared by incorporation of fillers. This review discusses the chemical methods for modification of dielectric elastomers, such as hydrosilylation, thiol-ene click chemistry, azide click chemistry, and atom transfer radical polymerization. The effects of the type and concentration of polar groups on the dielectric and mechanical properties of the elastomers and their performance in actuation and harvesting systems are discussed. State-of-the-art developments and perspectives of modified dielectric elastomers for deformable energy generators and transducers are provided.

Intrinsic Tuning of Poly(styrene–butadiene–styrene)-Based Self-Healing Dielectric Elastomer Actuators with Enhanced Electromechanical Properties

“…The deformable nature of the elastomers can also be maintained after modification. 1 Small polar groups including allyl cyanide, 14 3-mercaptopropionitrile [15][16] and 2-(methylsulfonyl)-ethanethiol, 17 and liquid crystal [18][19] have been grafted to various polymer structures resulting in an increase in their relative permittivity up to 22.7. 17 Grafting conducting poly(aniline) to poly(urethane) through a copper phthalocyanine ring resulted in a large increase in relative permittivity to 105.…”

On thermo-viscoelastic experimental characterization and numerical modelling of VHB polymer

“…In this case, three major techniques have actively been explored, e.g. polymers filled with highly piezoelectric particles, polymer blends of two or more different dielectric polymers, and syntheses of new polymers with tailored actuation characteristics, see Alshammari et al [5], Dang et al [12], Ellingford et al [15], Keip et al [29], Hossain [22]. Despite such limitations, VHB is being considered as one of the most widely used EAP candidates for making actuator prototypes due to its moderate actuation properties, large stretchability, low susceptible to dielectric breakdowns, and commercial availability.…”

“…Note that we have two energy functions in the non-equilibrium viscous part, cf. Eqn (15). Hence, according to Eqn (17), they will end up with two evolution equations as the first one, using the Yeoh-type non-equilibrium energy function (15) 1 , becomeṡ…”

Silicone composites cured under a high electric field: an electromechanical experimental study

“…CNTs are widely being used to fabricate new composites of DEs for desirable dielectric and mechanical properties for transducer applications, see Ellingford et al 31 and Madsen et al 32 for exhaustive reviews on the material perspectives of DEs. Geng et al 33 prepared multi‐wall CNTs filled silicone rubber with the help of solvent evaporation method.…”