Interfacial polarization and dielectric properties of aligned carbon nanotubes/polymer composites: The role of molecular polarity

Sun, Haibin; Zhang, Haolin; Liu, Suting; Ning, Nanying; Zhang, Liqun; Wang, Yong

doi:10.1016/j.compscitech.2017.11.008

Cited by 81 publications

(36 citation statements)

References 33 publications

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“…By addition of CNT, clusters of non-conductive TPU and highly conductive CNT form higher capability of polarization. Consequently, adding higher percentage of CNT [69][70][71][72] increases the conductivity and initial capacitance, but lowers slope of polarity growth. Within higher CNT concentrations, larger polar islands are being formed on the TPU film in presence of an electric field ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Thermoplastic polyurethane flexible capacitive proximity sensor reinforced by CNTs for applications in the creative industries

Moheimani

Aliahmad

Aliheidari

et al. 2021

Sci Rep

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Wearable sensing platforms have been rapidly advanced over recent years, thanks to numerous achievements in a variety of sensor fabrication techniques. However, the development of a flexible proximity sensor that can perform in a large range of object mobility remains a challenge. Here, a polymer-based sensor that utilizes a nanostructure composite as the sensing element has been presented for forthcoming usage in healthcare and automotive applications. Thermoplastic Polyurethane (TPU)/Carbon Nanotubes (CNTs) composites are capable of detecting presence of an external object in a wide range of distance. The proximity sensor exhibits an unprecedented detection distance of 120 mm with a resolution of 0.3%/mm. The architecture and manufacturing procedures of TPU/CNTs sensor are straightforward and performance of the proximity sensor shows robustness to reproducibility as well as excellent electrical and mechanical flexibility under different bending radii and over hundreds of bending cycles with variation of 4.7% and 4.2%, respectively. Tunneling and fringing effects are addressed as the sensing mechanism to explain significant capacitance changes. Percolation threshold analysis of different TPU/CNT contents indicated that nanocomposites having 2 wt% carbon nanotubes are exhibiting excellent sensing capabilities to achieve maximum detection accuracy and least noise among others. Fringing capacitance effect of the structure has been systematically analyzed by ANSYS Maxwell (Ansoft) simulation, as the experiments precisely supports the sensitivity trend in simulation. Our results introduce a new mainstream platform to realize an ultrasensitive perception of objects, presenting a promising prototype for application in wearable proximity sensors for motion analysis and artificial electronic skin.

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Section: Resultsmentioning

confidence: 99%

Thermoplastic polyurethane flexible capacitive proximity sensor reinforced by CNTs for applications in the creative industries

Moheimani

Aliahmad

Aliheidari

et al. 2021

Sci Rep

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“…The FT-IR and XRD datahas also revealed that the composites do not belong to a homogeneous system as the all the characteristic peaks of both components have been obtained. For such a semi heterogeneous system the high dielectric constant values are well explained on the basis of Maxwell-Wagner-Sillars effect [53,54]. When there are two media in contact that possess different conductivities and permittivity space, charges build up at their interfaces [55,56].…”

Section: Resultsmentioning

confidence: 99%

“…The polarization at the interfaces of the amorphous and crystallite phases and the molecular polarity especially due to N–H bond is the major cause of dielectric losses [54]. As shown in the SEM micrographs the porosity has greatly increased in the 5% of BaTiO 3 /Ppy which restricted the charge transport between the grains, the major cause of dielectric loss (εʺ) [51].…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of BaTiO3/Polypyrrole Composites with Exceptional Dielectric Behaviour

et al. 2018

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Higher concentrations of ceramic fillers induce brittleness in the ceramic/polymer hybrids which restrict their applications to limited fields especially when such hybrids are prepared for their use as dielectrics. We have synthesized and characterized different BaTiO3-polypyrrole (PPy) composites by changing the concentration of BaTiO3 from 1% by weight of PPy taken to 5 wt % to explore its effect on the dielectric parameters of the final product and found that the BaTiO3-polypyrrole composite with weight ratio of 0.05:1 exhibited highest dielectric constant, lowest dielectric loss and thermally most stable. All the composites were prepared using in-situ polymerization of pyrrole in an aqueous dispersion of low content of BaTiO3 in the presence of small amount of Hydrochloric acid. These composites were characterized for their microstructure and crystallinity by X-ray diffractometer (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) while thermal stability by thermo gravimetric (TGA) analysis. An impedance analyser (LCR meter) was utilized to investigate the dielectric parameters. FT-IR data confirmed the presence of the two phases and their interaction, inferred from the shifting of normal PPy peaks. The data obtained from XRD confirmed the presence of crystallites of 2.8 to 5 nm with dominant crystallinity of the filler, TGA analysis (25 to 600 °C) confirmed the higher thermal stability induced on successive addition of the filler into the prepared composites as compared to that of pure PPy in a wide temperature range which is unusual for such a low % age addition of the filler. The SEM analysis together with XRD results reveal that the successive introduction of BaTiO3 particles produced crystallites of 2 to 5 nm size which bonded together and changed the hemispherical shaped larger grains of the matrix to regular shaped smaller grains. The dielectric constant of the composites was enhanced with filler contents from 178 to 522 at 1 MHz for 1 wt % and 5 wt % BaTiO3 respectively. It was concluded that the introduction of BaTiO3 into the polymer matrix with this new procedure has greatly affected the polymerization process, thermal stability, morphology and dielectric properties of the host matrix and has resulted in a novel series of the composites which may have broad applications.

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“…[47] As the frequency increases (10 3 to 10 6 Hz), the contribution from interfacial polarization decreases, giving rise to an overall decrease in the dielectric constant values. [4,28,48] The interfacial polarization effect is considered negligible beyond 10 6 Hz. For our sample, we achieve ε r ≈ 4.68 for PU+h-BN and ≈2.92 for plain PU, a 1.6 times increase in ε r due to h-BN incorporation at 10 6 Hz.…”

Section: Dielectric Measurementsmentioning

confidence: 99%

Hexagonal Boron Nitride–Enhanced Optically Transparent Polymer Dielectric Inks for Printable Electronics

Zhu

et al. 2020

Adv Funct Materials

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Solution-processable thin-film dielectrics represent an important material family for large-area, fully-printed electronics. Yet, in recent years, it has seen only limited development, and has mostly remained confined to pure polymers. Although it is possible to achieve excellent printability, these polymers have low (≈2-5) dielectric constants (ε r). There have been recent attempts to use solution-processed 2D hexagonal boron nitride (h-BN) as an alternative. However, the deposited h-BN flakes create porous thin-films, compromising their mechanical integrity, substrate adhesion, and susceptibility to moisture. These challenges are addressed by developing a "one-pot" formulation of polyurethane (PU)-based inks with h-BN nano-fillers. The approach enables coating of pinhole-free, flexible PU+h-BN dielectric thin-films. The h-BN dispersion concentration is optimized with respect to exfoliation yield, optical transparency, and thin-film uniformity. A maximum ε r ≈ 7.57 is achieved, a twofold increase over pure PU, with only 0.7 vol% h-BN in the dielectric thinfilm. A high optical transparency of ≈78.0% (≈0.65% variation) is measured across a 25 cm 2 area for a 10 μm thick dielectric. The dielectric property of the composite is also consistent, with a measured areal capacitance variation of <8% across 64 printed capacitors. The formulation represents an optically transparent, flexible thin-film, with enhanced dielectric constant for printed electronics.

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Interfacial polarization and dielectric properties of aligned carbon nanotubes/polymer composites: The role of molecular polarity

Cited by 81 publications

References 33 publications

Thermoplastic polyurethane flexible capacitive proximity sensor reinforced by CNTs for applications in the creative industries

Thermoplastic polyurethane flexible capacitive proximity sensor reinforced by CNTs for applications in the creative industries

Synthesis and Characterization of BaTiO3/Polypyrrole Composites with Exceptional Dielectric Behaviour

Hexagonal Boron Nitride–Enhanced Optically Transparent Polymer Dielectric Inks for Printable Electronics

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