Interfacial charge storage mechanisms of composite electrodes based on poly(ortho-phenylenediamine)/carbon nanotubes via advanced electrogravimetry

To reach a deeper understanding of the charge storage mechanisms of electrode materials is one of the challenges toward improving their energy storage performance. Herein, we investigate the interfacial ion exchange of a composite electrode made of carbon nanotube/poly( ortho-phenylenediamine) (CNT/P oPD) in a 1M NaCl aqueous electrolyte via advanced electrogravimetric analyses based on electrochemical quartz crystal microbalance (EQCM). Classical EQCM at different scan rates of the potential revealed the complex electrogravimetric behavior likely due to multi-species participation at different temporal scales. Thereafter, in order to better understand the behavior of each species (ions, counter ions, and co-ions) in the charge compensation mechanism, the electrogravimetric impedance spectroscopy analysis (also called ac-electrogravimetry) was pursued. Ac-electrogravimetry revealed the role of each species where Na+ cations and Cl− anions as well as protons participate in the charge compensation mechanism of the CNT/P oPD composite with different kinetics and proportions. The water molecules with opposite flux direction with the cations are also detected, suggesting their exclusion during cationic species transfer. Having analyzed ac-electrogravimetry responses in depth, the synergistic interaction between the CNT and P oPD is highlighted, revealing the improved accessibility of species to new sites in the composite.

Electroconductive and photoactive poly(phenylenediamine)s with antioxidant and antimicrobial activities for potential photothermal therapy

In recent years, polyaniline derivatives such as poly(phenylenediamine)s have attracted the attention of researchers due to their better solubility, good optical and electrical properties. In the current work, poly(ortho- phenylenediamine)...

Optical Properties of Composites Based on Poly(o-phenylenediamine), Poly(vinylenefluoride) and Double-Wall Carbon Nanotubes

In this work, synthesis and optical properties of a new composite based on poly(o-phenylenediamine) (POPD) fiber like structures, poly(vinylidene fluoride) (PVDF) spheres and double-walled carbon nanotubes (DWNTs) are reported. As increasing the PVDF weight in the mixture of the chemical polymerization reaction of o-phenylenediamine, the presence of the PVDF spheres onto the POPD fibers surface is highlighted by scanning electron microscopy (SEM). The down-shift of the Raman line from 1421 cm⁻¹ to 1415 cm⁻¹ proves the covalent functionalization of DWNTs with the POPD-PVDF blends. The changes in the absorbance of the IR bands peaked around 840, 881, 1240 and 1402 cm⁻¹ indicate hindrance steric effects induced of DWNTs to the POPD fiber like structures and the PVDF spheres, as a consequence of the functionalization process of carbon nanotubes with macromolecular compounds. The presence of the PVDF spheres onto the POPD fiber like structures surface induces a POPD photoluminescence (PL) quenching process. An additional PL quenching process of the POPD-PVDF blends is reported to be induced in the presence of DWNTs. The studies of anisotropic PL highlight a change of the angle of the binding of the PVDF spheres onto the POPD fiber like structures surface from 50.2° to 38° when the carbon nanotubes concentration increases in the POPD-PVDF/DWNTs composites mass up to 2 wt.%.

Emulsion and miniemulsion techniques in preparation of polymer nanoparticles with versatile characteristics

In recent years, polymer nanoparticles (PNPs) have found their ways into numerous applications extending from electronics to photonics, conducting materials to sensors and medicine to biotechnology. Physical properties and surface morphology of PNPs are the most important parameters that significantly affect on their exploitations and can be controlled through the synthesis process. Emulsion and miniemulsion techniques are among the most efficient and wide-spread methods for preparation of PNPs. The objective of this review is to present and highlight the recent developments in the advanced PNPs with specific properties that are produced through emulsion and miniemulsion processes.

Spectroscopic and Biophysical Interaction Studies of Water-soluble Dye modified poly(o-phenylenediamine) for its Potential Application in BSA Detection and Bioimaging

Ultrasound-assisted synthesis of water soluble poly(o-phenylenediamine) (POPD) and its doping with Acid Orange (AO), Fluorescein (Fluo) and Rhodamine-6G (R6G) dyes was carried out with a view to enhance the photophysical properties of POPD. XPS studies confirmed that doping of POPD occured through hydrogen bonding between NH group of POPD and C=O/SO-, S=O groups of the dyes. The presence of strong hydrogen bonding was also confirmed via UV-vis studies by the addition of urea and sodium chloride to the dye modified POPD adducts. Molar extinction coefficient of these adducts was found to bear a close relationship with the molecular structure. Fluorescence life time, (τf,) was found to be lowest (1.8 ns) for AO-POPD and highest (3.2 ns) for Fluo-POPD. The structure of AO-POPD was more strained, while that of Fluo-POPD was least strained. Intrinsic fluorescence decay constant, (k0f) showed increasing values for POPD, AO-POPD, Fluo-POPD, R6G-POPD as 0.071, 0.072, 0.153, and 0.172 (108 s-1), which could be correlated to the increasing strain-free molecular structure of the adducts. Circular dichroism spectra (CD) of BSA in presence of POPD and R6G- POPD revealed that it partially broke its helical structure, while Fluo-POPD and AO-POPD showed enhancement in the helical content. The 3-D fluorescence studies confirmed enhancement in hydrophobicity of POPD and R6G- POPD and increase in hydrophylicity of AO-POP and Fluo-POPD in the microenvironment of tryptophan residue-213 of BSA. Fluo-POPD and R6G-POPD adducts were chosen to find out the lowest detection limit (LOD) of BSA by differential pulse voltammetry (DPV) which was found to be 1.35 nM, and 1.65 nM using Fluo-POPD and R6G -POPD respectively. The binding constant of BSA with Fluo-POPD- and R6G-POPD was obtained as 3.98 × 106 Lmol-1 and 5.27 × 102 Lmol-1. These polymers could therefore, be used for the detection of BSA. Live cell imaging revealed that POPD nanoparticles were bound to the outer membrane of E. coli, while R6G-POPD, showed penetration into the cytoplasm and excellent labeling of E. coli. This facile technique could be used to design tunable biomarkers by tailoring the conjugated polymer with a desired dye molecule.

Experimental and DFT studies of carbon nanotubes covalently functionalized with an imidazole derivative for electrochemical stability and green corrosion inhibition as a barrier layer on the nickel alloy surface in a sulphuric acidic medium

Nickel-based alloys are used for various applications such as in automobiles, superalloys and ship making. Their stability in acidic environments, however, is often not sufficient due to their native oxide films not withstanding harsh conditions. Carbon-based materials, in contrast, have shown high stability in acidic environments. In the present work, 4,5-diphenyl-imidazole-functionalized carbon nanotubes were investigated as a corrosion-inhibiting barrier layer on nickel alloy surfaces. We studied the corrosion inhibition efficiency of the imidazole-functionalized carbon nanotubes coated on nickel alloys. The materials were characterized using microscopy and spectroscopy methods. DFT studies were performed as well. The corrosion inhibition was evaluated using electrochemical methods. The imidazole-functionalized CNTs were shown to be crystalline and to have tubular structures. They displayed excellent corrosion inhibition on the nickel alloy surface.

(A) The electrostatic interaction of a functionalized carbon material with a 111 nickel surface, (B) the OPT structure of 4,5-DPM + CNT, and (C) 4,5-DPIM + CNT material chemisorbed on a 111 nickel alloy surface.

Synthesis of anticorrosion nanohybrid films based on bioinspired dopamine, L-cys/CNT@PDA through self-assembly on 304 stainless steel in 3.5% NaCl

Nanohybrid films containing multiwalled carbon nanotubes (MWCNTs) were successfully coated on 304-stainless steel (304ss) for anti-corrosion use. The nanocompositewas made by a self-assembly of poly (dopamine), wrapped with MWCNTs (CNT@PDA) through a mussel inspired method. In order to enhance the corrosion protection, an inner layer of L-cysteine, an adhesive amino acid to 304ss surface through thiol (-SH) functional group were constructed through a dip-coating process. Potentiodynamic polarization measurements and electrochemical impedance spectroscopy revealed that the double nano-layer could act as a noble anticorrosive coating in 3.5% NaCl, which was assigned to the hydrophobicity, robustness, and dense double layer coating.

Development and modification of conventional Ouali model for tensile modulus of polymer/carbon nanotubes nanocomposites assuming the roles of dispersed and networked nanoparticles and surrounding interphases

In this paper, conventional Ouali model for tensile modulus of composites is developed for polymer/carbon nanotubes (CNT) nanocomposites (PCNT) assuming the influences of filler network and dispersed nanoparticles above percolation threshold as well as the interphases between polymer host and nanoparticles which reinforce the nanocomposite and facilitate the networking. The developed model is simplified, because the characteristics of dispersed nanoparticles and surrounding interphase cannot significantly change the modulus of PCNT. The suggested model is compared to the experimentally measured modulus of some samples, which can calculate the percolation threshold of interphase regions and the possessions of interphase and filler network. The suggested model correctly predicts the influences of all parameters on the modulus. Thinner and longer CNT in addition to thicker interphase enhance the volume fraction of interphase which shifts the connectivity of interphase regions to smaller nanoparticle fraction and improves the modulus of PCNT. A very low level of percolation threshold significantly develops the modulus, but its high ranges have not any role. Among the studied parameters, the thickness and modulus of interphase between polymer host and networked nanoparticles play the most important roles in the modulus of PCNT.

A two-step model for the tunneling conductivity of polymer carbon nanotube nanocomposites assuming the conduction of interphase regions

This work develops a two-step model for the conductivity of polymer carbon nanotube (CNT) nanocomposites (PCNT) assuming the properties of tunneling and interphase regions.

A simple methodology to predict the tunneling conductivity of polymer/CNT nanocomposites by the roles of tunneling distance, interphase and CNT waviness

In this work, a simple methodology is presented that describes the main tunneling conductivity of polymer/CNT nanocomposites (PCNT) assuming the tunneling distance, interphase surrounding the CNT, and CNT waviness.

A model for tensile strength of polymer/clay nanocomposites assuming complete and incomplete interfacial adhesion between the polymer matrix and nanoparticles by the average normal stress in clay platelets

In this article, a model for tensile strength of polymer/clay nanocomposites (PCN) is suggested assuming perfect and imperfect interfacial adhesion between the polymer matrix and platelets by the average normal stress in clay platelets.