Polyazomethine with m-tolylazo side groups: thermal, dielectric and conductive behaviour

Bronnikov, Sergei; Kostromin, Sergei; Musteata, Valentina-Elena; Cozan, Vasile

doi:10.1080/02678292.2015.1025873

Cited by 26 publications

(9 citation statements)

References 29 publications

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“…Here, the thermal energy absorbed by the polarizable unit is small and, consequently, only small groups are able to follow the oscillations of an alternating electrical field. 42 Within this temperature range, the isochronal plots of PS NPs reveal a slight decreasing trend of ε′ as the temperature increases (Figure 5a) can be observed. According to a previous work by Sasabe et al 38 Values of ε′ and σ m are selected at 0.1 Hz.…”

Section: Nps Characterizationmentioning

confidence: 77%

Effect of Asymmetric Lobe Size on the Molecular Dynamics, Glass Transition, and Dielectric Behavior in Janus Nanoparticles

Asandulesa,

Solonaru,

Honciuc

2024

ACS Appl. Nano Mater.

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Janus nanoparticles (JNPs) characterized by their two-lobe asymmetrical structures serve as an exclusive platform for customizing the dielectric properties of materials. This investigation explores the influence of poly(3-(trimethoxysilyl)propyl methacrylate) (PTSPM) lobe size variations on the dielectric behavior of JNPs, employing dielectric spectroscopy across a wide temperature range. Initial analysis of seed polystyrene (PS) nanoparticles (NPs) displays characteristics typical of nonpolar polymers, indicating low dipolar activity in their frequencydependent permittivity (ε′(f)) profiles. However, with the addition of PTSPM, snowman-shaped PS−PTSPM JNPs exhibit heightened dipolar behavior, tapering at higher frequencies owing to PTSPM's low dipole-frequency response. Temperature-dependent permittivity (ε′(T)) profiles unravel a distinct β-relaxation process at lower temperatures, linked to localized motions within the PTSPM polar lobe. As the PTSPM lobe size increases, this relaxation proportionally intensifies, displaying increasingly larger activation energies. Remarkably, shifts in glass transition temperatures (T g ) in the JNPS series suggest hindered motions of PS chains in the PS lobe, attributed to the growth of the PTSPM lobe. This systematic investigation reveals a correlation between the asymmetric architecture of JNPs and their dielectric behavior, shedding light on the underlying mechanisms behind the observed variations. Also, synthesizing surfactant-free JNPs assumes paramount importance, as the cleanliness of the interface significantly influences the dielectric properties of these NPs. By exploring the interplay between PTSPM lobe size, molecular dynamics, and glass transition temperatures, this study provides valuable insights into tailoring dielectric properties for advanced functional materials.

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Section: Nps Characterizationmentioning

confidence: 77%

Effect of Asymmetric Lobe Size on the Molecular Dynamics, Glass Transition, and Dielectric Behavior in Janus Nanoparticles

Asandulesa,

Solonaru,

Honciuc

2024

ACS Appl. Nano Mater.

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“…For the reference (matrix) PAZ sample, relaxation processes could clearly be recognized both at low ( γ ‐ and β ‐relaxations) and at high ( α ‐relaxation) temperatures; the last is strongly overlapped with ac conductivity. Detailed analysis, attribution, and analytical description of these relaxation processes have been presented . However, for the PAZ/rGO:MWCNTs nanocomposites these relaxation processes are manifested not so clearly.…”

Section: Resultsmentioning

confidence: 99%

“…Its basic characteristics are as follows: number‐average molecular weight M n = 1800 g/mol, weight‐average molecular weight M w = 2000 g/mol, and polydispersity index PDI = 1.12. Detail information on PAZ synthesis and its physical characteristics has been announced . Since PAZ macromolecule contains side chains, it possesses a valuable dipole moment which is a favorable criterion for BDS analysis.…”

Section: Methodsmentioning

confidence: 99%

Morphology, structure, and segmental dynamics in polyazomethine/hybrid carbon nanofillers composites

et al. 2019

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The polyazomethine/hybrid carbon nanofillers composites were fabricated. The nanofilles were comprised of thermally reduced graphene oxide (rGO) and multi‐walled carbon nanotubes (MWCNTs) varying in rGO:MWCNTs ratio; the total nanofillers loading was 1 wt%. The scanning electron miscroscopy images revealed uniform distribution of the hybrid nanofillers and formation of 3D networks between rGO and MWCNTs. Molecular dynamics of the polymer chains in these nanocomposites was investigated with broadband dielectric spectroscopy. The polymer fragility, the dielectric glass transition temperature, and the dielectric relaxation strength of the nanocomposites were evaluated and analyzed depending on the rGO:MWCNTs ratio. The thermal glass transition temperature and the thermal relaxation strength evaluated from the differential scanning calorimetry data were shown to behave in other manner. This behavior was interpreted in terms of a fraction of polymer being immobilized in an interfacial layer around the nanoparticles.

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“…The dielectric relaxation processes were analyzed in detail by fitting each ε″( f ) dependency according to Havriliak‐Negami (HN) expression and the HN fitting procedure of ε″( f ) dependencies was performed with WinFit software package provided by Novocontrol . The sub‐glass relaxation processes are known to follow the Arrhenius equation:

τ_{\max} false(T false) = τ_{normalo} exp (\frac{E_{a}}{R T})

where τ max is the relaxation times associated with the peak maxima, τ 0 is a preexponential factor, E a is the apparent activation energy of the corresponding dipolar process, and R is the gas constant .…”

Section: Resultsmentioning

confidence: 99%

Thermal and electrical behavior of hybrid thermosets based on epoxy and maleimide resins cured with p‐aminobenzoic acid

Mustaţă¹,

Tudorachi²,

Asăndulesa³

et al. 2019

Int J of Chemical Kinetics

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Two thermoset systems based on maleimides and diglycidyl ether of bisphenol A (DGEBA) cured with p‐aminobenzoic acid were characterized in terms of thermal and electrical behavior. Thermal characterization has been undertaken by means of thermogravimetric analysis in nitrogen atmosphere up to 600°C using simultaneous thermogravimetric/Fourier transform infrared/mass spectrometry (TG/FT‐IR/MS) analysis. In the first stage of thermal degradation, the global kinetic parameters [activation energy (Ea) and preexponential factor (log A1 (s−1))] were calculated using the isoconversional method of Friedman. The energies variation as well as the shape of the differential thermal analysis curves suggests that the thermal decomposition process occurred in multiple stages. The evolved gases analysis was conducted by simultaneous TG/FT‐IR/MS coupled techniques. Dielectric relaxation spectroscopy characterization was also made.

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Polyazomethine with m-tolylazo side groups: thermal, dielectric and conductive behaviour

Cited by 26 publications

References 29 publications

Effect of Asymmetric Lobe Size on the Molecular Dynamics, Glass Transition, and Dielectric Behavior in Janus Nanoparticles

Effect of Asymmetric Lobe Size on the Molecular Dynamics, Glass Transition, and Dielectric Behavior in Janus Nanoparticles

Morphology, structure, and segmental dynamics in polyazomethine/hybrid carbon nanofillers composites

Thermal and electrical behavior of hybrid thermosets based on epoxy and maleimide resins cured with p‐aminobenzoic acid

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