High‐Permittivity Polysiloxanes for Solvent‐Free Fabrication of Dielectric Elastomer Actuators

Szczepanski, Johannes von; Opris, Dorina M.

doi:10.1002/admt.202201372

Cited by 9 publications

(9 citation statements)

References 37 publications

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“…The major drawback of high‐permittivity polymers is the reduced dielectric breakdown field, which is significantly lower than commercial PDMS with ≈50–70 V µm −1 (Figure 4c). [ 18,21,22,26 ] The critical breakdown strength of the new elastomer is lower than PDMS, but higher compared to previously reported polysiloxane composites with similar high permittivity. [ 48 ] The electrical breakdown field was 21.93 ± 1.57 V µm −1 with a Weibull form factor of 6.80.…”

Section: Resultsmentioning

confidence: 84%

“…This contrasts previous works on PP, where increased PP often leads to higher capacitive losses. [21,26] Creating a discontinuous phase through the capillary suspension might be responsible for decreasing capacitive losses. This approach could have far-reaching implications, as most polar polymers suffer from high capacitive losses, which might be significantly improved by adding a small amount of silica and PDMS and creating capillary suspensions.…”

Section: Elastomer Electromechanical Propertiesmentioning

confidence: 99%

“…[15,[18][19][20]22] Additionally, only a few multi-layered structures consisting of three active layers have been reported for polar polysiloxanes (PP), demonstrating the additional processing challenges this new class of materials faces even on well-established thin-film techniques. [19,21,[23][24][25][26] As with polar polysiloxane inks, conventional polydimethylsiloxane (PDMS) inks require significant modification to be processable by DIW. Reliable extrusion requires that DIW inks meet certain rheological criteria.…”

Section: Introductionmentioning

confidence: 99%

“…[ 15,18–20,22 ] Additionally, only a few multi‐layered structures consisting of three active layers have been reported for polar polysiloxanes (PP), demonstrating the additional processing challenges this new class of materials faces even on well‐established thin‐film techniques. [ 19,21,23–26 ]…”

Section: Introductionmentioning

confidence: 99%

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Polysiloxane Inks for Multimaterial 3d Printing of High‐Permittivity Dielectric Elastomers

Danner,

Pleij,

Siqueira

et al. 2023

Adv Funct Materials

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Dielectric elastomer transducers (DET) are promising candidates for electrically‐driven soft robotics. However, the high viscosity and low yield stress of DET formulations prohibit 3D printing, the most common manufacturing method for designer soft actuators. DET inks optimized for direct ink writing (DIW) produce elastomers with high stiffness and mechanical losses, diminishing the utility of DET actuators. To address the antagonistic nature of processing and performance constraints, principles of capillary suspensions are used to engineer DIW DET inks. By blending two immiscible polysiloxane liquids with a filler, a capillary ink suspension is obtained, in which the ink rheology can be tuned independently of the elastomer electromechanical properties. Rheometry is performed to measure and optimize processibility as a function of filler and secondary liquid fraction. Including polar polysiloxanes as the secondary liquid produces a printed elastomer exhibiting a four‐fold permittivity increase over commercial polydimethylsiloxane. The characterization and multimaterial printing into layered DET devices demonstrates that the immiscible capillary suspension improves the processability of the inks and enhances the properties of the elastomers, enabling actuation of the devices at comparatively low voltages. It is anticipated that this formulation approach will allow soft robotics to harness the full potential of DETs.

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Section: Resultsmentioning

confidence: 84%

Section: Elastomer Electromechanical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Polysiloxane Inks for Multimaterial 3d Printing of High‐Permittivity Dielectric Elastomers

Danner,

Pleij,

Siqueira

et al. 2023

Adv Funct Materials

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“…6 This can be achieved by introducing polar side groups to the polymer backbone and thus increasing the material's polarizability. [7][8][9][10][11][12] From the large number of different side groups that have been tested, nitrile groups stand out with a large increase in permittivity and high stability under ambient conditions. 13 Just like natural muscles, DEAs are exposed to the risk of damage.…”

Section: Introductionmentioning

confidence: 99%

Self-healable, high-permittivity elastomers for dielectric elastomer actuators

Szczepanski

Danner

Opris

2023

Electroactive Polymer Actuators and Devices (EAPAD) XXV

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Polar group-modified polysiloxanes obtained by anionic ring-opening polymerization possess high dielectric permittivity and are of great interest for application in dielectric elastomer actuators (DEAs). A self-healing elastomer can be obtained by in situ polymerization and cross-linking using a cyclic siloxane monomer with polar side groups and a cross-linker consisting of multiple connected siloxane rings. In previous works, a non-polar cross-linker has been used, which requires the addition of a solvent for compatibilization with the polar monomer. In polymerization reactions of siloxanes, the addition of solvent leads to a more pronounced formation of cyclic by-products. These cycles impair the mechanical properties of the elastomer and cannot be removed after the reaction, as the material is already cross-linked. Therefore, in this work, we use a polar cross-linker that can be mixed with the polar monomer without adding solvent. Nitrile groups have been studied extensively for increasing the permittivity of the polysiloxane backbone. For a functionalization of 100%, a dielectric permittivity of ~18 was reached. In most cases, the nitrile group was attached to the siloxane backbone in the form of cyanopropyl groups. Still, the influence of the alkyl spacer on the material's dielectric and mechanical properties has not been studied. In this work, we synthesize cyanoalkyl-functional cyclic siloxanes with different lengths of the alkyl spacer and polymerize them solvent-free to high-permittivity polysiloxanes.

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High‐Permittivity Polysiloxanes for Bright, Stretchable Electroluminescent Devices

von Szczepanski,

Wolf,

et al. 2024

Advanced Optical Materials

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Stretchable alternating current electroluminescent (ACEL) devices have a bright future in wearable electronics and soft robotics. Still, their market application is hindered by high operating voltages. The voltage can be reduced by increasing the relative permittivity of the dielectric elastomer in the emissive layer. Here, a fluorine‐free high‐permittivity silicone elastomer functionalized with cyanopropyl side groups, specially designed for application in stretchable ACEL devices, is introduced. The polar silicone elastomer exhibits excellent mechanical properties and a dielectric permittivity four times higher than commercial PDMS. Light‐emitting devices based on the polar elastomer reach 7.5 times higher maximum luminance at the same electric field than PDMS‐based devices and turn on at a 50% lower electric field. Besides, the polar elastomer‐based devices perform better than all materials tested in literature in achieving high luminance at low electric fields. Stretchable ACEL devices are built from the polar elastomer which shows bright and uniform light emission and can be operated up to 50% strain. The high‐permittivity silicones are promising materials for stretchable ACEL devices and can help their breakthrough to market application by overcoming the drawback of high operating voltages.

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High‐Permittivity Polysiloxanes for Solvent‐Free Fabrication of Dielectric Elastomer Actuators

Cited by 9 publications

References 37 publications

Polysiloxane Inks for Multimaterial 3d Printing of High‐Permittivity Dielectric Elastomers

Polysiloxane Inks for Multimaterial 3d Printing of High‐Permittivity Dielectric Elastomers

Self-healable, high-permittivity elastomers for dielectric elastomer actuators

High‐Permittivity Polysiloxanes for Bright, Stretchable Electroluminescent Devices

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