Homogeneous dielectric elastomers with dramatically improved actuated strain by grafting dipoles onto SBS using thiol–ene click chemistry

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.…”

“…b,c) Properties of styrene–butadiene–styrene triblock copolymers modifiedwith different amounts of methylthioglycolate: DSC curves (b) and actuation strain as function of electric field (c). Reproduced with permission . Copyright 2016, The Royal Society of Chemistry.…”

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

“…The mechanical properties of the SBS:PVDF and MGSBS:PVDF blends depend on the PVDF concentration. For the SBS:PVDF blends, an increase in PVDF concentration leads to increased tensile strength and Young's modulus, see The reduced mechanical properties of MGSBS and the subsequent blends with PVDF can be explained by the presence of the methyl thioglycolate pendant groups, which introduces better phase mixing between the styrene and butadiene sections of the polymer [16], leading to a reduction in strength but an increase in the maximum strain of the material. When blended with PVDF, the ester groups of MGSBS increase the interactions with fluoro- alt-text: Fig.…”

“…By modification of SBS with methyl thioglycolate, the ester groups prevent π-π stacking, by altering the packing of the MGSBS chains through increased phase mixing between the styrene and butadiene blocks, compared to SBS chains.chains [16]. Without sufficient π-π stacking and a greater compatibility between MGSBS and PVDF, the MWCNTs will preferentially locate in the PVDF phase.…”

“…For example, with 89 mol% of grafting of allyl cyanide, ε reached 15.9, but this was at the expense of a high dielectric loss of 2.5.2.5 [7]. When grafting methyl thioglycolate to SBS via thiol-ene click chemistry, 81 mol% of grafting led to an increase in ε up to 12.2 [16] whilst grafting 100 mol% 2-(methylsulfonyl)-ethanethiol to poly(vinylmethylsiloxane) enhanced ε to 22.7.22.7 [17].…”