Poly(amidoamine) (PAMAM) dendrimers with different generations (G ¼ 2, 3 and 4) were synthesized, peripherally modified with aniline pentamers and studied for their redox and dopable behavior under different pH conditions. It was found that the electron transition of the p B -p Q band red-shifted and the size of PAMAM G2 decreased in an alkaline medium. The chemical oxidation process and the color change of these modified dendritic macromolecules were measured by cyclic voltammetry (CV) and electrochromism. All of the dendrimers showed three redox peaks in the CV. The current density of the voltammograms increased with increasing the number of aniline pentamer segments at the periphery. A drastic color change was observed when a linear potential sweep was applied. The thermal properties of the electroactive dendrimers were evaluated by differential scanning calorimetry and thermogravimetric analysis.

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A series of amphiphilic poly(amidoamine) dendrimers (PAMAM, G2-G5) composed of a hydrophilic core and a hydrophobic shell of aniline pentamer (AP) were synthesized and characterized. The modified dendrimers self-assembled to vesicular aggregates in water with the critical aggregation concentration (CAC) decreased in the order of G2 > G3 > G4 > G5. It was found that the modified dendrimers self-organized into spherical aggregates with a bilayer vesicular structures and that the dendrimers in higher generation have more order structure, which may be attributed to the crystallization induced by the compacted effect of AP segments. In addition, larger spherical vesicles were observed under acidic and alkaline conditions, as compared with sizes of aggregates in neutral medium. At low pH, the tertiary amine groups of PAMAM-AP were transformed to ammonium salts; the polarons were formed from AP units by doping with strong acids, thereby leading to the stability of vesicular aggregates being better than that in double distilled water. Nevertheless, in high pH environment, the deprotonation of PAMAM-AP caused the enhancement of π-π interactions, resulting in generation of twins or multilayered vesicles.

A organic soluble polyimide (SPI) prepared from 4,4'-Oxydianiline and 4,4'-(4,4'-Isopropylidenediphenoxy)bis(phthalic anhydride) was mixed with organo-modified montmorillonite (MMT) in N,N-Dimethylacetamide. The organic soluble polyimide-clay nanocomposite (PCN) materials were characterized by Fourier-Transformation infrared (FTIR), spectroscopy, wide-angle X-ray diffraction (WAXRD) patterns and transmission electron microscopy (TEM). It should be noted that the nanocomposite coating containing 3 wt% of clay loading was found to exhibit an observable enhanced corrosion protection on cold-rolled stell (CRS) electrode at higher operational temperature of 50 degrees C, which was even better than that of uncoated and electrode-coated with SPI alone at room temperature of 30 degrees C based on the electrochemical parameter evaluations. In this work, all electrochemical measurements were performed at a double-wall jacketed cell, covered with a glass plate, through which water was circulated from a thermostat to maintain a constant operational temperature of 30, 40 and 50 +/- 0.5 degrees C. Moreover, a series of electrochemical parameters shown in Tafel, Nyquist and Bode plots were all used to evaluate PCN coatings at three different operational temperatures in 5 wt% aqueous NaCl electrolyte. The molecular barrier properties at three different operational temperatures of SPI and PCN membranes were investigated by gas permeability analyzer (GPA) and vapor permeability analyzer (VPA).