Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers...

Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects.

Thermal camouflaging metamaterials

https://hal.archives-ouvertes.fr/hal-03333723/document

Polymer-based dielectrics with high permittivity for electric energy storage: A review

Dielectric elastomer generators (DEGs), which follow the physics of variable capacitors and harvest electric energy from mechanical work, have attracted intensive attention over the past decade. The lack of ideal dielectric elastomers, after nearly two decades of research, has become the bottleneck for DEGs’ practical applications. Here, we fabricated a series of polyurethane-based ternary composites and estimated their potential as DEGs to harvest electric energy for the first time. Thermoplastic polyurethane (PU) with high relative permittivity (∼8) was chosen as the elastic matrix. Barium titanate (BT) nanoparticles and dibutyl phthalate (DBP) plasticizers, which were selected to improve the permittivity and mechanical properties, respectively, were blended into the PU matrix. As compared to pristine PU, the resultant ternary composite films fabricated through a solution casting approach showed enhanced permittivity, remarkably reduced elastic modulus, and relatively good electrical breakdown strength,...

Dielectric Elastomer Generator with Improved Energy Density and Conversion Efficiency Based on Polyurethane Composites

Dielectric elastomer actuator composites (DEACs) are a class of electroactive polymers that are capable of changing shape or size once applied with an electric field. Such materials have found applications in artificial muscles, micro-robotics and micro air vehicles at industries. The dielectric behavior, mechanical properties, and electric breakdown strength are the main parameters for adjusting actuation behavior of DEACs. This review provides a brief introduction to the effect of 2-dimensional carbonic filler on the percolation threshold during the fabrication of these composites. The design process of graphene nanosheets (GNs) and their derivatives are described based on the filler structure: simple filler and complex filler. For each group, recent remarkable developments are illustrated and the technical issues demanding further improvement are discussed. In general, graphene-oxide (GO) and reduced-GO (rGO), as commutable GNs, numerous cases of use in DEACs have been reported where these materials were employed for controlling the reduction rate of dielectric breakdown strength, maintaining loss parameter (dielectric loss ( e ' ' ) and loss modulus ( E ' ' )), increasing electromechanical sensitively (β=dielectric permittivity ( e ' ) / elastic modulus) and improving the state of filler dispersion with interfacial engineering. The current review discusses the latest trends in research development in achieving such graphene-enabled enhancements. A systematic approach has been undertaken to highlight the advancements and challenges of graphene-based DEACs and the key research areas that need immediate attention.

Graphene-based composite for dielectric elastomer actuator: A comprehensive review

Dielectric, mechanical and electro-stimulus response properties studies of polyurethane dielectric elastomer modified by carbon nanotube-graphene nanosheet hybrid fillers

The electromechanical properties of diaphragm type actuator comprising hydrothermal reduced graphene oxide-polyurethane dielectric elastomer (RGO/PU) composites are described. Larger size graphene oxide (GO) nanoplates can be cut into smaller nanosheets during the hydrothermal conditions and the size of RGO nanosheets gradually decrease with pH value from 3 to 10. Small-size RGO nanosheets were introduced into PU dielectric elastomer matrix to obtain intelligent shape-changing polymer composites with high dielectric constant, high compliance and large electric field induced thickness strain. The RGO(pH10, 12 h)/PU-2.5 % composite film had a dielectric constant of 23.14 with a dielectric loss of 0.072 at 1 kHz. The composite film had a creep compliance of 3.211 × 10−5 1/Pa. At 38.5 MV/m, the electric field induced strain of RGO(pH10, 12 h)/PU-2.5 % is 56.5 %. The nanocomposites thus seem to be very attractive for Micro-Electro-Mechanical System applications.

Insight into effect of hydrothermal preparation process of nanofillers on dielectric, creep and electromechanical performance of polyurethane dielectric elastomer/reduced graphene oxide composites

A simple, cheap, all-organic process for the fabrication of polyurethane (PU) composites for dielectric elastomer actuators was presented in this paper This study focused on improving the electromechanical properties of PU matrix with polyol small organic molecule as filler The dielectric, tensile mechanical, dynamic thermal mechanical, creep, and electric field induced strain properties of a series of polyol-PU blends were described in detail It was found that the dielectric constant of PU at low frequencies (40–100 Hz) remarkably increased with the addition of polyols and the tensile strength of the PU/polyol blends decreased obviously with an increase in the content of polyol The polyol-PU all organic composites had better electromechanical response than the pristine PU Among the PU/glycerol, PU/ethylene glycol, and PU/triethylene glycol blends, PU/glycerol-50% had relatively high dielectric constant of 3271 (40 Hz), low tensile strength of 1637 MPa, low loss modulus of 16424 MPa (−40 °C), high compliance of 9709 × 10−5 1/Pa, and high electric field induced strain of 497 (374 MV/m) The enhancement of the electric field induced strain was mainly triggered by an increase of the dielectric constant and a decrease of the elastic modulus

Minchao Lin

Papers

Dielectric, mechanical and electro-stimulus response properties studies of polyurethane dielectric elastomer modified by carbon nanotube-graphene nanosheet hybrid fillers

Insight into effect of hydrothermal preparation process of nanofillers on dielectric, creep and electromechanical performance of polyurethane dielectric elastomer/reduced graphene oxide composites

Electromechanical response of polyol-polyurethane blends as dielectric elastomer flexible mirco-actuator material