Mapping the mechanical and electrical properties of commercial silicone elastomer formulations for stretchable transducers

Vaičekauskaitė, Justina; Mazurek, Piotr; Vudayagiri, Sindhu; Skov, Anne Ladegaard

doi:10.1039/c9tc05072h

Cited by 129 publications

(115 citation statements)

References 42 publications

(42 reference statements)

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“…Figure 2 shows that the reference elastomer Elastomer-V25, a typical non-filled silicone elastomer, can be maximally stretched to 130% with a Young´s modulus of 0.84 MPa. This value is consistent with reported values of Young's moduli for commercial silicone elastomers, which are in the range of 0.5-2.0MPa [27], [28]. As a comparison, Elastomer-HV15 exhibits a much lower Young´s modulus of 0.049 MPa, and a maximum strain of 1500%.…”

Section: Stress-strain Behaviorssupporting

confidence: 90%

Soft silicone elastomers with no chemical cross-linking and unprecedented softness and stability

Huang

Madsen

et al. 2020

Electroactive Polymer Actuators and Devices (EAPAD) XXII

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For silicone elastomers used as actuators, softness is key for enabling actuation at low voltages. Recently, an extremely soft (Young's modulus < 50 kPa) silicone elastomer without cross-links has been reported by Goff et al. Besides its extreme softness, the elastomer was reported to almost completely recover (82%) from a 10-cycle elongation of more than 5000%. This observation challenges conventional elasticity theory of cross-linked elastomers because a network without covalent crosslinks should not be able to strain-recover to such extent. In this work, the elastomer is hypothesized to be formed from concatenated rings through heterodifunctional uni-molecular ring closure. It is found that the elastic properties of this uncross-linked elastomer can be described by the dynamics of concatenated rings, which act as pseudo-crosslinks and pseudo-entanglements. Isolated rings and dangling rings function as external solvents and internal solvents respectively, thereby contributing to the unprecedented softness. The ability to precisely control the ratio between concatenated and dangling rings is expected to lead to even softer dielectric elastomers paving the way forward for ultra-soft robotics without significant mechanical losses.

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Section: Stress-strain Behaviorssupporting

confidence: 90%

Soft silicone elastomers with no chemical cross-linking and unprecedented softness and stability

Huang

Madsen

et al. 2020

Electroactive Polymer Actuators and Devices (EAPAD) XXII

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“…This is approximately 30% higher than the electrical breakdown strength of the reference coating (E_Ref), which is a commercial condensation curing silicone coating containing reinforcing fillers. It is also significantly higher than values reported for addition curing silicone elastomers, such as Sylgard, Ecoflex, and Elastosil [25]. Figure 11.…”

Section: Mechanically Stable Silicone Elastomer Films and Their Propementioning

confidence: 67%

Reliable Condensation Curing Silicone Elastomers with Tailorable Properties

Jurásková

Olsen²,

Dam‐Johansen

et al. 2020

Molecules

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The long-term stability of condensation curing silicone elastomers can be affected by many factors such as curing environment, cross-linker type and concentration, and catalyst concentration. Mechanically unstable silicone elastomers may lead to undesirable application failure or reduced lifetime. This study investigates the stability of different condensation curing silicone elastomer compositions. Elastomers are prepared via the reaction of telechelic silanol-terminated polydimethylsiloxane (HO-PDMS-OH) with trimethoxysilane-terminated polysiloxane ((MeO)3Si-PDMS-Si(OMe)3) and ethoxy-terminated octakis(dimethylsiloxy)-T8-silsesquioxane ((QMOEt)8), respectively. Two post-curing reactions are found to significantly affect both the stability of mechanical properties over time and final properties of the resulting elastomers: Namely, the condensation of dangling and/or unreacted polymer chains, and the reaction between cross-linker molecules. Findings from the stability study are then used to prepare reliable silicone elastomer coatings. Coating properties are tailored by varying the cross-linker molecular weight, type, and concentration. Finally, it is shown that, by proper choice of all three parameters, a coating with excellent scratch resistance and electrical breakdown strength can be produced even without an addition of fillers.

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“…LiCl, a highly hydratable salt, was selected as the conductive medium for this application due to the increased water retention in LiCl‐based hydrogels. [ 34 ] The hydrogel formulation consisted of 19.09 wt% LiCl, 9.01 wt% AAM, 0.004 wt% MBA, 0.326 wt% KPS, and 71.57 wt% DI water.…”

Section: Methodsmentioning

confidence: 99%

“…[ 33 ] Previously, the highest reported relative permittivity in HASELs was that of Ecoflex 00–30, ε r ≈ 3.4. [ 34 ] The self‐healing mechanism in the liquid dielectric allowed these actuators to withstand repeated electrical breakdown events before the silicone‐urethane began to suffer from irreversible damage (Figure 1d). By using 3D printing to fabricate a 3D array of 30 total soft capacitors, we synthesized a tentacle akin to the concept depicted in Figure 1e.…”

Section: Introductionmentioning

confidence: 99%

Rapid 3D Printing of Electrohydraulic (HASEL) Tentacle Actuators

O’Neill

Acome

Bakarich

et al. 2020

Adv Funct Materials

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A comprehensive material system is introduced for the additive manufacturing of electrohydraulic (HASEL) tentacle actuators. This material system consists of a photo-curable, elastomeric silicone-urethane with relatively strong dielectric properties (ε r ≈ 8.8 at 1 kHz) in combination with ionically-conductive hydrogel and silver paint electrodes that displace a vegetable-based liquid dielectric under the application of an electric field. The electronic properties of the silicone material as well as the mechanical properties of the constitutive silicone and hydrogel materials are investigated. The hydraulic pressure exerted on the dielectric working fluid in these capacitive actuators is measured in order to characterize their quasi-static behavior. Various design features enabled by 3D printing influence this behavior-decreasing the voltage at which actuation begins or increasing the force density in the system. Using a capacitance change of >35% across the actuators while powered, a demonstration of self-sensing inherent to HASELs is shown. Antagonistic pairs of the 3D printed actuators are shown to exert a blocked force of over 400 mN. An electrohydraulic tentacle actuator is then fabricated to demonstrate the use of this material and actuation system in a synthetic hydrostat. This tentacle actuator is shown to achieve motion in a multi-dimensional space.

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Mapping the mechanical and electrical properties of commercial silicone elastomer formulations for stretchable transducers

Abstract: Elastomers for fabricating soft and stretchable transducers require high elongation at break, high dielectric permittivity, high breakdown strength and low leakage current. We map blends of commercial silicones to find optimum compositions.

Cited by 129 publications

References 42 publications

Soft silicone elastomers with no chemical cross-linking and unprecedented softness and stability

Soft silicone elastomers with no chemical cross-linking and unprecedented softness and stability

Reliable Condensation Curing Silicone Elastomers with Tailorable Properties

Rapid 3D Printing of Electrohydraulic (HASEL) Tentacle Actuators

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