Largely improved electromechanical properties of thermoplastic dielectric elastomers by grafting carboxyl onto SBS through thiol–ene click chemistry

Abstract

Modified SBS with largely improved electromechanical properties is prepared by grafting carboxyl groups onto the polybutadiene domains using a simple, effective and controllable photochemical thiol-ene click reaction.

Polar Elastomers as Novel Materials for Electromechanical Actuator Applications

“…A styrene–butadiene–styrene triblock copolymer (SBS) was modified with different amounts of methylthioglycolate ( 22 ) or thioglycolic acid ( 23 ) by using thiol‐ene click chemistry ( Figure ) . As expected the T g 's increased with the amount of incorporated polar groups.…”

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

“…However, for the carboxylic acid modified SBS the mechanical properties are relatively poor. The material has a lower strength, T = 1.1 MPa, and the elastomer is less flexible and less ductile as Y = 3.3 MPa and λ max = 300% . From these results, modification of SBS with an ester group results in an elastomer with superior properties than a carboxylic acid modified SBS elastomer.…”

“…Typical reaction conditions for the modification of elastomers involve dissolving a photoinitiator such as 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA), elastomer and organic molecule in a solvent, and irradiation of the solution with UV light. The reaction is carried out without the need for an inert atmosphere, unless the organic molecule is at risk of becoming oxidized . The grafting level for thiol‐ene click chemistry is determined by how long the solution is exposed to UV light to induce the reaction, making the modification easily controlled.…”

“…Methyl thioglycolate and thioglycolic acid, which are similar‐sized groups but with an ester and carboxylic acid functionality, respectively, were grafted to SBS; see Table 7 . Grafting 83 mol% of thioglycolic acid resulted in an increase in the permittivity of SBS from ε r = 2.2 to ε r = 7.2, with a low dielectric loss of ε″ = 0.3 (TC2) . Grafting methyl thioglycolate to SBS also resulted in an elastomer with significantly improved dielectric properties, with an increased relative permittivity of ε r = 12.2 and a reduced loss of ε″ = 0.07 (TC1) .…”

Mechanical and dielectric properties of MWCNT filled chemically modified SBS/PVDF blends

“…The dielectric permittivity (ε) of dielectric elastomers such as poly(dimethylsiloxane)-(PDMS) [7] and styrene-butadiene-styrene (SBS) [8] is typically between 2~3, 2 and 3, semi-crystalline poly(vinylidene fluoride)-(PVDF) has an ε of 12.12 [9]. These are generally much lower than piezoelectric ceramic materials, such as lead zirconium titanate (PZT, ε~1300) ε ~ 1300) and barium titanate (BaTiO 3 , ε~1700).ε ~ 1700) [10].…”