Synthesis of solvent-free processable and on-demand cross-linkable dielectric elastomers for actuators

Caspari, Philip; Nüesch, Frank; Opris, Dorina M.

doi:10.1039/c9tc03391b

Cited by 19 publications

(22 citation statements)

References 57 publications

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“…It allows achieving soft elastic materials homogenous at the molecular level, with high dielectric permittivity and high dielectric breakdown strength. 16,28,29 The last parameter has a tremendous impact on the power generated by DEAs. It will also impact actuator lifetime since the device can be actuated at electric fields significantly below the critical breakdown field.…”

Section: Synthesis Of Elastomers With Increased Dielectric Permittivitymentioning

confidence: 99%

“…Crosslinking should be fast, reliable, quantitative, and should be completed after the trigger is removed. 29 Additionally, air, water, and film thickness should not impact the network formation. Cross-linking of end-groups allows the formation of more defined networks.…”

Section: Synthesis Of Elastomers With Increased Dielectric Permittivitymentioning

confidence: 99%

“…However, synthesizing polymers with controlled end groups is a great challenge in polymer chemistry and thus has been seldomly used for achieving polar polysiloxane elastomers. 29 The second approach gives less-defined networks with dangling chains and cross-linking points randomly distributed into the network.…”

Section: Synthesis Of Elastomers With Increased Dielectric Permittivitymentioning

confidence: 99%

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High dielectric permittivity elastomers: synthesis, processability, and device manufacturing

Sheima

Szczepanski

Danner

et al. 2022

Electroactive Polymer Actuators and Devices (EAPAD) XXIV

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The development of novel functional dielectric materials can open the doors to major technological innovations with societal impact. Stretchable capacitors transduce electrical into mechanical energy or vice-versa. Over the last 20 years, they have received significant interest from academia and industry. However, this technology still needs both improved dielectrics as well as conductive elastomers to achieve the desired low driving voltage and to realize devices with attractively high sensitivity. The currently most explored dielectric elastomers are polydimethylsiloxanes (PDMS). However, because of their low dielectric permittivity of only 3, the devices made of them require high voltages for operation.dielectric properties, and selected the most suitable groups to achieve the highest dielectric permittivity, yet sufficiently low glass transition temperature (T g ) to afford an excellent elastomer at room temperature after cross-linking. This research guided us to several promising polar polysiloxane elastomers modified with nitrile and nitroaniline groups, for which the properties were optimized. We reproducibly achieved dielectric elastomers with a dielectric permittivity of about 18. Some respond to a voltage as low as 200 V, while some give very large actuation and have a breakdown field reaching 100 V m -1 . By carefully selecting suitable synthetic chemistry, we could also achieve self-healable high permittivity elastomers. The materials can be processed into thin films by melt pressing. Stack actuators can be easily manufactured manually and give 5.4% actuation at an electric field as low as 3.2 V m -1 . Furthermore, the actuators can self-repair after a breakdown and be recycled after complete failure.A graphene nanoplatelets (GNPs) composite in PDMS as a conductive electrode was developed via in-situ polymerization. The synthesis and the processing by screen-printing were conducted solvent-free, making this composite the greenest electrode for this technology. This presentation gives an overview of recent research on improved materials for dielectric elastomer transducers (DETs) conducted at Empa. We are confident that our materials will impact fields including actuators, sensors, energy harvesting, artificial muscles, and soft robotics.

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Section: Synthesis Of Elastomers With Increased Dielectric Permittivitymentioning

confidence: 99%

Section: Synthesis Of Elastomers With Increased Dielectric Permittivitymentioning

confidence: 99%

Section: Synthesis Of Elastomers With Increased Dielectric Permittivitymentioning

confidence: 99%

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High dielectric permittivity elastomers: synthesis, processability, and device manufacturing

Sheima

Szczepanski

Danner

et al. 2022

Electroactive Polymer Actuators and Devices (EAPAD) XXIV

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“…As of now, a number of polar groups have been grafted to polysiloxane by us and other laboratories. − Occasionally, attractive permittivities have been reported, but a comparison of values from different laboratories is hampered by the fact that different molar masses, different dipole densities and end groups, as well as different synthetic procedures were used. The current paper tries to overcome this situation by a highly systematic approach.…”

Section: Introductionmentioning

confidence: 99%

Polysiloxanes Modified with Different Types and Contents of Polar Groups: Synthesis, Structure, and Thermal and Dielectric Properties

et al. 2021

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Polymers with high dielectric permittivity are promising for the construction of next-generation transducers and energy storage devices with improved energy density. Here, we report the synthesis, glass-transition temperature (T g ), and dielectric properties of polysiloxanes with different polarities. For this, we set out from poly(dimethyl-co-methylvinyl)siloxanes with different vinyl group content. The vinyl groups were then transformed into polar groups of various nature by an efficient one-step thiol−ene addition postpolymerization modification. We used the resulting collection of materials to establish structure− property relationships, side group design, and thermal and dielectric properties. Our results show that the T g increases with the polar group content and the strength of the polar group. A similar trend is observed for the dielectric permittivity as long as the T g of the polymer is well below 0 °C. Smaller polar groups tend to show a smaller increase in T g , and an increased linker length helps to decreases T g , which is generally favorable for high permittivity. Our findings guided us to design polysiloxanes with a permittivity as high as 27.7 and a T g of −18.2 °C. To the best of our knowledge, this is the highest dielectric permittivity of a polymer with a T g well below room temperature.

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“…[ 5 ] When a voltage is exerted on the surface of compliant electrodes, as a consequence, the DE film is compressed along thickness and expanded in area to generate actuated strains due to the Maxwell stress, and thus converts electrical energy into mechanical energy. [ 6–8 ] According to the Pelrine formula ( S z = P / Y = − ε ′ ε 0 E 2 / Y , where ε ′ is the dielectric constant, ε 0 is the permittivity of vacuum, E is the electric field, and Y is the elastic modulus. ), [ 5 ] it can be inferred that high‐performance DEA requires high dielectric constant, high electric field and low elastic modulus.…”

Section: Introductionmentioning

confidence: 99%

Ternary silicone dielectric elastomer micro‐nanocomposites with enhanced mechanical and electromechanical properties

et al. 2020

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In this paper, ternary silicone dielectric elastomer micro‐nanocomposites were prepared by mixing barium titanate (BT) nanoparticles or 3‐mercaptopropylethoxy‐bis(tridecyl‐pentaethoxy‐siloxane) (Si747)‐modified BT (BT‐Si747) with hexagonal boron nitride (BN) microplatelets into methyl vinyl silicone rubber (MVSR). BN platelets as physical barriers improve the dispersion of BT nanoparticles, so the MVSR/BT/BN composites achieve the higher electric breakdown field. The Si747 in MVSR/BT‐Si747/BN composites can be grafted on BT nanoparticles surface while the mercapto groups of Si747 can react with double bonds of MVSR, which increases interfacial interaction to improve the mechanical property. As a result, the tensile strength and elongation at break of MVSR/30 wt%BT‐Si747/30 wt%BN composite are 3.43 MPa and 2705%, which is 2.4 and 4.4 times as high as the MVSR/30 wt%BT/30 wt%BN composite, respectively. The MVSR/BT‐Si747/BN composites exhibit higher actuation performance under lower electric fields due to simultaneous increase in dielectric constant and decrease in elastic modulus. The MVSR/10 wt%BT‐Si747/10 wt%BN composite obtains an actuated strain of 8.81% at 47.48 kV/mm, which is twice as high as pure MVSR (4.4% at 60.21 kV/mm). The used method in this experiment is simple, effective, and low cost, and prepared ternary micro‐nanocomposites have potential applications in dielectric actuators.

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Synthesis of solvent-free processable and on-demand cross-linkable dielectric elastomers for actuators

Abstract: On-demand and solvent-free synthesis of high permittivity polysiloxane elastic thin films responsive to an electric stimulus is presented.

Cited by 19 publications

References 57 publications

High dielectric permittivity elastomers: synthesis, processability, and device manufacturing

High dielectric permittivity elastomers: synthesis, processability, and device manufacturing

Polysiloxanes Modified with Different Types and Contents of Polar Groups: Synthesis, Structure, and Thermal and Dielectric Properties

Ternary silicone dielectric elastomer micro‐nanocomposites with enhanced mechanical and electromechanical properties

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