Impedance spectroscopy study of dehydrated chitosan and chitosan containing LiClO4

Costa, M. M.; Terezo, Ailton José; Matos, Anna Lívia Linard; Moura, W.A.; Giacometti, J.A.; Sombra, A. S. B.

doi:10.1016/j.physb.2010.08.011

Cited by 20 publications

(8 citation statements)

References 23 publications

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“…CS can be obtained from different sources, including insects, fungi, molluscan organs, and crustacean shells . The main feature differentiating CS polymers from other biopolymers is the presence of two hydroxyl (OH) groups and one amine (NH 2 ) functional group (electron‐donating groups) in its backbone structure . Previous reports have confirmed that the existence of lone‐pair electrons on the functional groups of polar polymers are responsible for complexation and the reduction of silver ions to silver nanoparticles .…”

Section: Introductionmentioning

confidence: 99%

A novel polymer composite with a small optical band gap: New approaches for photonics and optoelectronics

Aziz

Abdullah

Rasheed

2017

J of Applied Polymer Sci

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In this article, a novel approach is presented for the preparation of small band-gap polymer composites. The intensity of the surface plasmon resonance (SPR) peak increased from 0.64 to 3.2 for the chitosan-silver nitrate sample containing 1 wt % titanium dioxide (TiO 2 ). In the cases of 3 and 5 wt % added TiO 2 particles, the SPR peak disappeared. A wide shift of the absorption coefficient from 4.36 to 0.93 eV was observed. The smallest optical band gap of about 0.98 eV was achieved for the sample containing 3 wt % TiO 2 filler. The wide shift in the optical band gap was interpreted on the bases of the formation of metal-induced gap states between the metallic silver particles and the TiO 2 structure. A novel approach was achieved that was an alternative method to Tauc's semi-empirical model for band-gap estimation. The optical dielectric loss parameter for the band-gap study was easily calculated and analyzed, whereas it unfolded a deep knowledge from the physics point of view. The established quantum mechanical expression revealed a strong relationship between the energy band gap and the optical dielectric loss parameter. The scanning electron microscopy results show the leakage of white aggregated silver particles and distinguishable intense peaks of metallic silver particles between 3 and 3.3 keV appearing in the energy-dispersive X-ray spectrum.

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Section: Introductionmentioning

confidence: 99%

A novel polymer composite with a small optical band gap: New approaches for photonics and optoelectronics

Aziz

Abdullah

Rasheed

2017

J of Applied Polymer Sci

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“…Thus, the polycationic nature of chitosan due to the abundance of free amino (NH 2 ) groups (Scheme 1(b)) on the backbone of chitosan makes it possible to produce ionconducting polymer electrolyte [9]. This is related to the fact that the amine groups in chitosan structure can act as electron donors and interact with inorganic salts [10], and therefore chitosan meets an important requirement for acting as a polymer host for the solvation of salts [11]. One of the major reasons for poor ionic conductivity and concentration polarization has been attributed to the possibility of an ionassociation (ion-pairing) effect.…”

Section: Introductionmentioning

confidence: 99%

Role of Dielectric Constant on Ion Transport: Reformulated Arrhenius Equation

Aziz

2016

Advances in Materials Science and Engineering

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Solid and nanocomposite polymer electrolytes based on chitosan have been prepared by solution cast technique. The XRD results reveal the occurrence of complexation between chitosan (CS) and the LiTf salt. The deconvolution of the diffractogram of nanocomposite solid polymer electrolytes demonstrates the increase of amorphous domain with increasing alumina content up to 4 wt.%. Further incorporation of alumina nanoparticles (6 to 10 wt.% Al2O3) results in crystallinity increase (large crystallite size). The morphological (SEM and EDX) analysis well supported the XRD results. Similar trends of DC conductivity and dielectric constant with Al2O3concentration were explained. The TEM images were used to explain the phenomena of space charge and blocking effects. The reformulated Arrhenius equation (σ(ε′,T)=σoexp(-Ea/KBε′T)) was proposed from the smooth exponential behavior of DC conductivity versus dielectric constant at different temperatures. The more linear behavior of DC conductivity versus1000/(ɛ′×T)reveals the crucial role of dielectric constant in Arrhenius equation. The drawbacks of Arrhenius equation can be understood from the less linear behavior of DC conductivity versus1000/T. The relaxation processes have been interpreted in terms of Argand plots.

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“…The saturation of M / at higher frequency may be due to non-existent dipole orientation [37]. Such behavior indicates that, these materials are very capacitive in nature [38]. No relaxation peak was observed in M / spectra because M / in complex electric modulus (M * ) is equivalent to  / in complex permittivity ( * ).…”

Section: Electric Modulusmentioning

confidence: 99%

Electric Modulus and Scaling of Chitosan/PVA Biopolymer Blend

Ahmed

Elhendawy²,

Elqahtani

et al. 2021

Egypt. J. Chem.

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Dielectric measurements of chitosan/PVA polymer blends were performed at various temperatures in a wide frequency range.Higher values of  ' and '' at higher temperatures and lower frequencies are correlated to interfacial polarization (IP) and DC conduction, respectively. Isochronal behavior of // against temperature revealed that chitosan and PVA is characterized by a dipolar relaxation peak at T= 393 K and 348 K, respectively. The activation energy (Ea) values of conduction have been estimated for all samples. Cole-Cole behavior revealed that, with increasing the temperature the semicircles area of the samples increased and the semicircle intercept are shifted towards higher value of / indicating that, the capacitance is increased. Complex electric modulus (M*) of all samples is investigated and it is found that, real part (M/) of the complex electric modulus showed nonlinear behavior with frequency, whereas, (M//), i.e., the imaginary part, is characterized by a relaxation peaks for all samples. The scaling behavior has been carried out at T= 333 K, as a representative temperature and it is found that, all the curves are overlapped leading to a master curve indicating that, dynamic process is temperature independent.

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Impedance spectroscopy study of dehydrated chitosan and chitosan containing LiClO4

Cited by 20 publications

References 23 publications

A novel polymer composite with a small optical band gap: New approaches for photonics and optoelectronics

A novel polymer composite with a small optical band gap: New approaches for photonics and optoelectronics

Role of Dielectric Constant on Ion Transport: Reformulated Arrhenius Equation

Electric Modulus and Scaling of Chitosan/PVA Biopolymer Blend

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