On the Spectroscopic Analyses of Polytetrafluoroethylene Coated with Nano ZnO and SiO2

Author(s):  
Maroof A. Hegazy ◽  
Rasha Ghoneim ◽  
Hend A. Ezzat ◽  
Heba Y. Zahran ◽  
Ibrahim S. Yahia ◽  
...  

Abstract On polytetrafluoroethylene (PTFE) polymer nanocomposites coated with basically two metal oxides (MOs), SiO2 and ZnO, as well as a mixture of the two MOs, density functional theory (DFT) computations were performed. The B3LYPL/LAN2DZ model was used to evaluate PTFE polymer nano composites suggested model structures. The physical and electrical properties of PTFE modified on surface with ZnO and SiO2 coated layer by layer change Total dipole moment (TDM) and HOMO/LUMO band gap energy ∆Eto be 13.0082 Debye and 0.6889 eV, respectively. Moreover, TDM and band gap energy (∆E) improved to 10.6053 Debye and 0.2727 eV, respectively, when the nanofiller was increased to 8 atoms. In addition, the results of the Molecular Electrostatic Potential (MESP) and the Quantitative Structure Activity Relationship (QSAR) showed that PTFE coated with ZnO and SiO2 improved electrical characteristics and thermal stability. As PTFE coated with ZnO and SiO2 layer by layer, all stability characteristics, including electrical and thermal stability, were enhanced. The improved PTFE can be used as a corrosion-inhibiting layer for astronaut suits, according to the predicted results.

2019 ◽  
Vol 8 (2) ◽  
pp. 553-557 ◽  

Model molecules for sodium carboxymethyl cellulose (Na-CMC) (monomer), glycerol, acetic acid and Na-CMC-glycerol-acetic acid are optimized with Density Functional Theory (DFT) at B3LYP/3-21G*. For the optimized models, total dipole moment (TDM), the highest occupied and lowest unoccupied molecular orbitals (HOMO/LUMO band gap energy), and molecular electrostatic potentials (ESP) are calculated at the same method to give an explanation for the possibility of using Na-CMC-Glycerol-acetic acid model molecule in electrochemical devices, gas sensors and batteries. As a result of the substitution of Na-CMC with glycerol, TDM increased from 7.7141 Debye to 22.4942 Debye which is approximately equal to three times that of Na-CMC. However, HOMO/LUMO band gap energy decreased from 0.9040 eV to 0.5072 eV. After the addition of acetic acid to Na-CMC-glycerol model, TDM increased to24.7270 Debye and HOMO/LUMO band gap energy decreased to 0.4939 eV. Both TDM and HOMO/LUMO band gap energy values are improved by increasing the acetic acid units, where TDM became 25.3510 Debye and HOMO/LUMO band gap energy decreased to 0.3815 eV. The results of ESP indicated that the addition of glycerol and acetic acid to Na-CMC increased the electronegativity of Na-CMC which in turn enhanced its electronic properties.


2016 ◽  
Vol 675-676 ◽  
pp. 15-18 ◽  
Author(s):  
Sasfan Arman Wella ◽  
Irfan Dwi Aditya ◽  
Triati Dewi Kencana Wungu ◽  
Suprijadi

First principle calculation is performed to investigate structural and electronic properties of strained silicene (silicon analogue of graphene) when absorbing the hydrogen sulfide molecule gas. Two configuration of silicene-H2S system, center and hollow configuration, is checked under 0% (pure), 5%, and 10% uniaxial engineering strain. We report that the silicene-H2S system in center configuration has larger binding energy compare to the silicene-H2S system in hollow configuration. The results show that H2S is physisorbed on silicene. In this work, we also find the change of band gap energy (~60 meV) is appearing when H2S interacted with silicene in center configuration, whereas the band gap energy of silicene has no change when interacted with H2S in hollow configuration.


Author(s):  
Ying Xuan Ng ◽  
Rashid Ahmed ◽  
Abdullahi Lawal ◽  
Bakhtiar Ul Haq ◽  
Afiq Radzwan ◽  
...  

The knowledge of the structural and electronic properties of a material is important in various applications such as optoelectronics and thermoelectric devices. In this study, we are using full potential linearized augmented plane wave method framed within density functional theory provided by WIEN2k to optimize the structure of PdSe2 in orthorhombic (Pbca) phase and calculate its electronic properties. With the implementation of local density approximation (LDA), Perdew-Burke-Ernzerhof parameterization of generalized gradient approximation (PBE-GGA), Wu-Cohen parameterization of GGA (WC-GGA), and PBE correction for solid GGA (PBEsol-GGA), the computed results of lattice constants are found to be within 5% error with the experiment data. Also, our calculated indirect band gap energy was found to be ~0.24 eV by LDA along with modified Becke-Johnson potential functional (mBJ) with experimental lattice constants and ~0.52 eV by using PBE-GGA with optimized lattice constants. However, the effect of spin-orbit coupling is not found too much on the band gap energy. By analyzing the partial density of states, we identify that d-orbital of Pd is demonstrating a slightly more significant contribution to both the valence and conduction band near to Fermi level which is also in agreement with the previous first principles study.


2014 ◽  
Vol 971-973 ◽  
pp. 119-122
Author(s):  
Hai Ping Wang

The transition phase and electronic properties of LiBH4 were investigated by ab initio plane-wave pseudopotential density functional theory method. According to the theoretical calculation, the phase sequence Pnma → P21/c → Cc is obtained. The phase transitions Pnma → P21/c and P21/c → Cc are at the pressure of 1.64 GPa and 2.83 GPa, respectively, by total energy-volume data. As the pressure increases, the value of the band gap energy is reduced from 7.1 (Pnma) to 6.1 eV (Cc). Moreover, the electronic properties of the high pressure phases are discussed. The electronic properties are linked to the band gap energy, total (partly) density of states and atoms (bond) populations.


2019 ◽  
Vol 9 (4) ◽  
pp. 4143-4149 ◽  

Study of the effect of some Nano metal oxides MOs as CuO, OCu, ZnO and OZn on some bio-polymers as Cellulose, Chitosan and Sodium Alginate. Thus, model structure of two unit organic polymer Cellulose, Chitosan and Sodium Alginate and they with Nano MOs as CuO, OCu, ZnO and OZn are suggested. Density functional theory (DFT) conducted to study this effect atB3LYP/LANL2DZ. Computed HOMO-LUMO band gap energy(∆E) and Total dipole moment (TDM) indicated that Cellulose and Chitosan affected by Nano MOs that TDM increased and ∆E decrease while Sodium Alginate has a slight change that has no effect on it. Also, calculated electrostatic potential (ESP) indicated that Cellulose and Chitosan affected by Nano MOs specially with CuO while Sodium Alginate has no effect.


2016 ◽  
Vol 64 (2) ◽  
pp. 157-161
Author(s):  
M Alauddin ◽  
MM Islam ◽  
MA Aziz

The structural, spectroscopic (IR, NMR and UV-Vis), electronic and optical properties of monohydrated adenine (monohydrated 6-aminopurine, C5H5N5.H2O) are investigated theoretically using DFT/B3LYP level of theory. Three minimum energy structures have been identified for monohydrated of adenine where H2O molecule is doubly hydrogen bonded with adenine.1H NMR analysis shows that the protons which are hydrogen bonded become deshielded and chemical shift moves to the higher frequency region.Five IR active mode of vibrations were found at 3108, 3295, 3665, 3676 and 3719 cm-1 which are assigned as bonded -OH vibration of H2O, Bonded -NH vibration of NH2, Free -NH vibration of adenine (9 N), Free -NH vibration of NH2, Free -OH vibration of H2O, respectively and agree well with the available experimental results. The investigation of electronic properties shows that the HOMO-LUMO band gap energy of monohydrated adenine at B3LYP level is 5.15 eV. The major electronic transition (from HOMO to LUMO (83%) (π→π*)) occurs at 258 nm (4.80 eV) with a minor transition at 237 nm (5.23 eV). Theoretically it is observed that the HOMO-LUMO band gap energy is for monohydrated adenine is lower than that of adenine. Dhaka Univ. J. Sci. 64(2): 157-161, 2016 (July)


2016 ◽  
Vol 4 (1) ◽  
Author(s):  
A.N. Bakiev ◽  
O.A. Mayorova ◽  
A.A. Gorbunov ◽  
I.V. Lunegov ◽  
E.V. Shklyaeva ◽  
...  

AbstractTwo new D-π-A chromophores composed of an electron-donating carbazole unit linked through π- bridges, bearing 3,4-ethylenedioxythiophene (EDOT) moiety, with an electron withdrawing dicyanovinyl group (DCV) were successfully synthesized involving Suzuki or Heck cross-coupling and Knöevenagel reactions as the key steps. The obtained compounds absorb light over a broad spectral range, including the visible spectrum. The HOMO/LUMO energies and band gap energy values (Eg) were calculated on the basis of the experimental optical and electrochemical data: HOMO, LUMO, Eg (eV), −5.51, −3.14, 2.37 (4), −5.34, −3.14, 2.20 (7). The presence of the HC=CH unit in compound 7 resulted in the increase of the HOMO energy level, the decrease of a band gap value and red shifts of the absorption and emission bands in comparison with those of 4. Large Stokes shifts and broadband luminescence inherent to both chromophores suggest their use as materials for luminescent solar collectors (LSCs). The obtained compounds demonstrated good solubility and suitable thin-film forming properties. For this reason, they may be suitable for solution-processable photovoltaic applications.


2018 ◽  
Vol 41 (3-4) ◽  
pp. 67-71 ◽  
Author(s):  
Özgür Alver ◽  
Cemal Parlak ◽  
Mustafa Şenyel ◽  
Ponnadurai Ramasami

Abstract Fullerenes and heteroatom doped fullerenes exhibit high potential as drug delivery agents in sensor technology and medical applications. We investigated, using density functional theory, the possible interaction sites and the nature of interaction, adsorption energy assessments, band gap energy evaluations, charge transfer analyses, and some diagnostic vibrational band assignments for valproic acid (VPA) and aluminum, silicon, and boron decorated fullerene systems. The present research shows that VPA has strong interaction with the doped fullerene cages particularly at its carbonyl edge. Therefore, these doped fullerenes can be suggested as possible drug delivery agents.


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