Papers by Keyword: Oxidative Polymerization

Abstract: Stable electronic configuration between the interface of an n-type oxide semiconductor core and a p-type polymer shell is necessary in order to guarantee a consistent functioning core-shell structure. This research aims to use silane-aniline to link between an n-type Titanium (IV) oxide (TiO₂) core and p-type polyaniline emeraldine salt (PANI-ES) shell. Core-shell structure was created by functionalizing TiO₂ powders with silane aniline molecules using simple soaking technique and then polymerizing the attached aniline molecules using an oxidative technique. Infrared spectroscopy reveals the presence of Si-O bonds signifying the presence of linkage between the inorganic core and polymeric shell. Polymerization of the attached aniline molecules may have led to coupling of aromatic rings to form long polymeric structures which caused widening and shifting of aromatic rings’ IR peak to lower wavenumber. In conclusion, silane-aniline was successfully utilized to connect the n-type TiO₂ core and p-type PANI-ES shell.

Abstract: Oxidative polymerization of benzylidenephenylenediamines produced polymers containing conjugated double bonds. Kinetic studies of the processes of oxidative polymerization of benzylidenephenylene diamines were carried out. The obtained kinetic dependencies allowed us to suggest the mechanism of oxidative polymerization of benzylidenephenylenediamines, which flows through the stage of formation of the cation radical, dimmer, tetramer, leading eventually to the formation of the polymer. In this case the limiting stadia is the formation of cation-radical, and chain growth occurs by N-C. A study of the thermal properties of the polymers showed that polybenzylidenephenylenediamines is characterized by rather high values of heat resistance. It was found that the process of destruction of most of the synthesized polymers occurs in several stages and depends on the chemical structure of the macromolecule.

Abstract: Oxidative polymerization of 3-amino,2'-,(3')-nitrodiphenylazomethine was carried out in various ways. A possible mechanism for the polymerization of 3-amino,2'-,(3')- nitrodiphenylazomethine, where chain growth occurs as type N-C, is shown. It has been found that the yield of the polymer product is affected by the polymerization process and time. The chemical structure of the polymers obtained is established. The study of the thermal properties of polymers showed a low thermal stability and the process of destruction proceeds in two stages.

Abstract: Silica-modified polyaniline (SM-PAni) were deposited on glass and platinum-coated glass substrates via oxidative polymerization. Zinc sulfide (ZnS) were grown on top of SM-PAni films by chemical bath deposition. The surface and optical characteristics were investigated. SEM micrographs revealed the formation of SM-PAni nanostructures and ZnS nanospheres. Increase in nanosphere sizes were observed when Pt-coated substrates were used. UV-Vis spectra showed that SM-PAni/ZnS nanocomposites grown on both substrates exhibit good absorbance in the visible and ultraviolet region which is a good indication for potential solar cell application. Better absorbance in the ultraviolet region was observed when Pt-coated substrates was used. Vibrational peaks observed in FTIR confirmed the presence of SM-PAni particles.

Abstract: Among the conducting polymers, polyaniline is of vital importance as an electronicmaterial [1{4] because of its easy synthesis, environmental stability, reversible proton dopabil-ity, redox recyclability, cost-e ectiveness, and reasonable electrical conductivity. Electrical andoptoelectronic applications of conducting polymers often require high current densities thatcan be achieved by either heavy doping or a high-level carrier injection. Polyaniline occurs infour oxidation states (i.e., leucoemeraldine, emeraldine base, emeraldine salt, and pernigrani-line), out of which only emeraldine salt is conductive in nature (the others are insulating innature). Polyaniline (PANI) exists in a variety of forms that di er in chemical and physicalproperties [5{9].Polyaniline is one of the most promising conducting materials for applications in optoelec-tronics and microelectronics devices.The doping of polyaniline can be accomplished through protonic acid and oxidative doping.Protonic acid doping of emeraldine base units results in complete protonation of imine nitrogenatoms to give the fully protonated emeraldine salt [10, 11].The AC (alternative current) conductivity properties of Polyaniline (PANI) and doped PANIparallel plate materials were investigated by impedance spectroscopy. The real part of conduc-tivity (0), and the real part of impedance (Z0p) were measured in the logarithmic frequencyrange of 100 to 1.5x107 Hz at 25, 40, 50 and 100 C temperatures. The AC conductivity value ofthe undoped PANI is high values for polymeric materals to ionic conduction and electrode po-larization in low frequency. The alternative current (AC) conductivity increases with increasingMB concentration and the frequency.

Abstract: Poly (3, 4-ethylenedioxythiophene) (PEDT) has attracted a great deal of interest during the last decades. PEDOT was popular with many applications such as antistatic coating, the hole injection layer in OLED. The thermal stability of PEDOT is important in these applications. In this study, PEDOT films were prepared by oxidative polymerization on the substrate polyimide (PI) films. Matrix polymer poly (vinyl prrrolidone) (PVP), Monomer 3, 4-ethylenedioxythiophene), retardant were dissolved in solvent as monomer solution; The Iron (III) p-toluenesulfonate hexahydrate (FTS) was used as oxidant solution. To investigate the heating properties of PEDOT films, the content of PVP, oxidant FTS, retardant were varied. The influence of treatment current density was also studied. Thickness of the PEDOT film was measured by Alpha-step surface profiler and the surface resistivity was measured by multimeter.

Abstract: Conducting attapulgite/titania/polyaniline/ (ATP/TiO₂/PANI) core-shell nanocomposites (CSNs) were synthesized via oxidative polymerization of aniline after the surface modification of the ATP carried with TiO₂ nanoparticles. The structure and morphology of the ATP/TiO₂/PANI CSNs were characterized by X-ray diffraction, scanning electron microscopy, and fourier transform infrared. The thermal stability of the ATP/TiO₂/PANI CSNs was also investigated by thermal analyzer. The results show that the ATP/TiO₂/PANI CSNs display “capsule like” core-shell structure, of which ranging in diameter of about 80 nm and length of about 250 nm. In addition, the ATP/TiO₂/PANI CSNs present a higher degree of crystallization and better thermal stability. We believe that the excellent core-shell structure and better thermal stability should be prone to improve their other properties and enlarge their application.

Abstract: Polypyrrole (Ppy)-coated viscose fibers have been prepared by vapor phase and liquid phase pyrrole deposition technique, respectively. Comparative morphological and electrical property analysis was carried out on the viscose fiber prepared with both vapor and liquid phase processes. The result showed the configuration of Ppy coatings and electrical property had a strong relation with the deposition technique. Ppy-coated viscose fiber prepared by vapor phase show a high uniform polypyrrole coatings, fine Ppy granular structure, lower electrical resistance, and good fastness performances to abrasion.

Abstract: UHMWPE fibers have widely application, but the poor adhesion to polymer matrix limit its development. Polymerization of vapor phase pyrrole on UHMWPE fibers was introduced in this paper for improve the adhesion between UHMWPE fibers and epoxy. The Ppy-coated UHMWPE fiber was studied by SEM, FTIR, DSC and pullout test, respectively. The result showed that there is no chemical act between UHMWPE fiber and polypyrrole. The Ppy coatings have strong effect on the morphological and adhesion property of UHMWPE fiber. The most important, the maximum pullout force was improved after pyrrole polymerization on the surface of UHMWPE fiber.

Abstract: Typical conductive polymers of poly(3-alkylthiophenes) were synthesized by oxidative polymerization. Polythiophene with no side chain was also electrolyticaly polymerized. Alkyl side chains were CnH2n+1 with n=4, 6, 8, 12. The regioregularity with the HT linkage was larger than 99% based on NMR analysis. We have evaluated the effect of side chain size on the thermoelectric properties of Seebeck coefficient and electrical conductivity. The results were as follows: 1) Seebeck coefficient decreased with an increasing electrical conductivity. 2) High Seebeck coefficient >1mV/K was observed at low electrical conductivity <10-2S/cm. 3) Small side chains, especially no side chain caused higher thermoelectric properties of polythiophene series.