Two component polyurethane coatings are widely used for materials protection. Herein, a series of acrylic polyurethane coatings were prepared by reaction of hydroxyl acrylic resin and hexamethylene diisocyanate (HDI) biuret. These coatings have different isocyanate to hydroxyl ratios (expressed as NCO/OH). The degradation process of the coatings was evaluated by electrochemical impedance spectroscopy measurement. Then, the results were analyzed using equivalent electrical circuits. Besides, the adhesion and water resistance of the coatings were also investigated. Experimental results demonstrated that the higher the NCO/OH ratios within a certain range, the better the corrosion resistance. Specifically, the coating with NCO/OH = 1.4 provided the best corrosion resistance, and its impedance modulus still remained at close to 1 × 1011 ohms per cm2 after 50 days immersion. However, the corrosion resistance of coatings with NCO/OH = 0.8 and NCO/OH = 1.0 were relatively poor. More interestingly, with the increase in NCO/OH ratios, the coating's adhesion increased slightly and the water resistance improved noticeably.

•Polyaniline grafted basalt plates were prepared by chemical-oxidation polymerization.•PANI was adhered to the surface of basalt plates by chemical bonds or hydrogen bonds instead of physical forces.•The protective performance of the coatings were improved dramatically by incorporated 10% PANI-g-BP (1:4).Polyaniline-graft-basalt plates (PANI-g-BP) were prepared based on γ-aminopropyltriethoxysiliane (APTS)-modified basalt plates via in-situ chemical-oxidation polymerization method. Three PANI-g-BP samples were prepared by varying the ratio of aniline to BP, i.e. 1:2, 1:4, 1:6. The results of Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermo gravimetric analysis (TGA) confirmed that PANI was successfully grafted on the surface of basalt plates. Different coatings were prepared by adding the synthesized PANI-g-BPs or PANI, and were coated on the mild steel subsequently. The water-uptake property, the adhesion strength and the passive properties of the coatings were investigated. In addition, the protective performance of the coatings was tested by the electrochemical impedance spectroscopy (EIS) in 12% NaCl solution at 95 °C. The results indicated that the coatings with 10% PANI-g-BP (1:4) exhibited the best protective performance and its impedance at 0.01 Hz is higher than 1010 after 80 days immersing.

The spherical silica particles in narrow size distribution with different diameters of 90 nm, 200 nm, 320 nm and 400 nm were prepared by the modified Stöber method and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The phase composition of particles was characterized by X-ray diffraction. The results indicated that each of the silica particle samples was in amorphous state. The shear thickening fluids (STFs) comprising 53 vol.% of silica particles and 47 vol.% of polyethylene glycol with molecular weight of 200 g mol−1 (PEG200) were prepared and evaluated. The influence of size and size distribution on the critical shear rate and the intensity of shear thickening were analyzed. The STFs prepared by silica nanoparticles with a diameter of 90 nm showed the giant rheological effect with the critical shear rate of 2.51 s−1, the largest viscosity of 45,500 Pa∙s and the yield stress of 181 kPa. The experiments and the analysis results demonstrated that the suspensions prepared by nanoparticles have high intensity of shear thickening.

•Narrow size distributed silica nanoparticles were synthesized in large scale.•Effect of nitric acid on the DST behavior of silica particle fluids was investigated.•Effect of temperature on the DST behavior of silica particle fluids was investigated.The discontinuous shear thickening (DST) phenomenon of silica nanoparticle suspensions was investigated in this article. First, the non-aggregated silica nanoparticles were synthesized and characterized. The results indicate that the silica nanoparticles are spherical particles with a narrow size distribution with a diameter of approximately 90 nm. Next, the influence of nitric acid concentration and temperature on the DST phenomenon of shear thickening fluids (STFs) was investigated. The results indicate that the concentrated fluids with nitric acid concentration below 8.50 mmol/L and at a temperature below 40 °C exhibit a readily noticeable DST phenomenon.The effect of concentration of nitric acid on the discontinuous shear thickening phenomenon of silica nanoparticle suspension.

Multifunctional conductive polymers with CN conjugated system and functional groups were prepared by polycondensation of carbamide at high temperature under elevated pressure. The corresponding molecular structures of these polycondensation of carbamide products (PCA) were proposed according to the analysis of elemental analysis, FT-IR spectra, UV–Visible absorption spectra and X-ray photoelectron spectroscopy. The morphology of the obtained products can be tuned by controlling the synthesis conditions such as temperature, pressure and catalyst used in the synthesis process. X-ray diffraction (XRD) patterns confirmed the existence of relatively ordered crystal structures for these polymers. Corrosion protection performance of as-prepared coatings with PCAs was investigated based on NaCl solution immersion test. The results indicated that PCA-2 nanoparticles can improve the protection performance for metals by increasing the adhesion strength of the epoxy coatings and acting as crosslinking points to form a dense film.

•The highly importance of electrochemical activity of electrode materials on energy storage system.•Inactive component’ content greatly affects the overall activity of electrode materials.•High electrochemical active PANI was prepared.•PANI hybrids with different contents of hydroxyethyl cellulose (HEC) were prepared and characterized.The efficiency of an energy storage device is closely related to the reversibility and electrochemical activity of the electrode materials. Although polyaniline (PANI) has been used to fabricate various electrochemical devices, its electrochemical activity has not received enough attention. Here, high reversible electrochemical active PANI nanofibers are prepared and mixed with hydroxyethyl cellulose (HEC). Their supercapacitive performance is investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) techniques on Pt electrodes. The results show that the obtained PANI has reversible electrochemical activity on Pt electrode. But the electrochemical activity decreases gradually with the increase of HEC content and even disappears when the HEC content reaches 30%. It suggests that the content of the inactive materials should be controlled strictly to guarantee the electrochemical activity of the electrode materials in fabricating high performance electrochemical energy storage devices.

Hierarchical architectures attract a large number of scientists and engineers because of their unique physicochemical properties compared with bulk materials and their precursors. It is believed that intermolecular interactions play a key role in the formation of these hierarchical architectures. However, the principle of coordination of various intermolecular interactions in the self-assembly process is not clear. Here, an aniline oligomer is used as a model brick to study the formation process of well-defined hierarchical architectures, and the directional growth mechanism is proposed. It is assumed that aniline oligomer molecules are asymmetric, and driven by intermolecular attractive forces to aggregate in various manners. Combined with the interactions between the aniline oligomer and molecules from the medium, three-dimensional assemblies, flower-like and urchin-like microspheres, can be formed. The variability and complexity of morphologies produced in the process was analyzed according to the intermolecular interactions, which includes hydrogen bonding, π–π stacking, hydrophobic interaction, etc. The applicability of these special hierarchical architectures, such as in the preparation of superhydrophobic surfaces, is also discussed.

•Extraordinarily high stable polyaniline/graphite electrodes were prepared and they can maintain stable for 30,000 cycles without any decrease in specific capacitance values in LiClO4/propylene carbonate.•Polyaniline morphology is changed from smooth dense film into porous morphology which is beneficial for dopants diffusion and the utility of polyaniline.•The upper limit potential of the supercapacitor can be as high as 1.0 V in LiClO4/propylene carbonate which is beneficial for energy density and power improvement.•Polyaniline films formed by casting solution and evaporation solvent are mechanically robust.Polyaniline is one of the most studied conductive polymers used for fabricating pseudo-capacitors, but its low cycling stability impedes its application. This low cycling stability is closely related to the degradation of PANI, in which water plays an important role. To address this problem, non-aqueous solution (LiClO4/propylene carbonate or LiClO4/propylene carbonate/ethylene carbonate) is used as the supporting electrolyte to test the capacitive performance of PANI on graphite electrodes (PANI/GR). Experimental results show that the PANI/GR electrodes can maintain stable for 30,000 cycles without any decrease in specific capacitance values. Furthermore, the degradation of PANI can be avoided even when the upper limit potential is increased to 1.00 V vs. SCE. Consequently, this non-aqueous system is beneficial in improving both the cycling stability and energy density of PANI based pseudo-capacitors, which shows great promising application in sustainable and environmentally friendly energy storage devices.

Epoxy microcapsules and polyaniline nanofibers are incorporated into epoxy/polyamide coatings to enhance the protective and self-healing performance of the coatings for mild carbon steel. Epoxy microcapsules are prepared through the well-known interfacial polymerization process. Sodium chloride (NaCl, 12 wt %) solution is used as the model corrosion media. Protective and self-healing performance of the coatings is characterized by the electrochemical impedance spectroscopy (EIS) technique, scanning electron microscope (SEM) image analysis, and X-ray photoelectron spectroscopy characterization. The results demonstrate that the coatings containing epoxy microcapsules and polyaniline nanofibers have almost no deterioration in the 100-day testing period under the condition of being immersed in 12 wt % NaCl solutions at room temperature. The excellent protective performance and self-healing behavior are ascribed to the controlling release of epoxy which is encapsulated and the passive property of PANI nanofibers. The results might give some insights on the preparation of high performance protective coatings.

Polyaniline nanomaterials were successfully prepared by potentiostatic polymerization method, and then post-treated by the aqueous solution containing HClO4 and H2O2, I2, FeCl3, or APS, respectively. The product was dried under vacuum condition at least 72-h, and then it was characterized by SEM, FTIR and UV–Vis techniques. While product treated with H2O2 was weighed, an accident, an explosion of polyaniline nanowires broke out. Here, experimental process is reported in detail and the explosive mechanism is proposed, and thus providing a warning for PANI nanomaterials research and production.

High quality microspheres self-assembled from nanowires of polyaniline (PANI) are prepared by a self-assembly process using ammonium peroxydisulfate as oxidant in aqueous solution. The microspheres of about 2.6 μm average diameter are composed of uniform nanowires with 40–60 nm in diameter. The formation process of PANI microsphere indicates that its evolution of morphologies can be divided into three stages. First, a large quantity of PANI nanowires form, then porous microspheres develop, and finally most of nanowires transform into microspheres. The morphology and uniformity of the PANI microspheres mainly depend on the mole ratio of aniline to ammonium peroxydisulfate. The BET specific surface area and conductivity of the polyaniline porous microsphere at room temperature are 53 m2 g− 1 and 3.3 × 10−1 S cm− 1, respectively.

The growth process of polyaniline (PANI) nanofibers during the electrochemical polymerization was investigated in detail. The nano-fibrillar morphology appears to be intrinsic to PANI, and the unique character is attributable to a combined effect of electrophilic substitution reaction mainly taking place at the para-position of aniline or its oligomers and aniline oligomers with one-dimensional (1D) structure. Interestingly, the PANI film formed on the electrode exhibits a lamellar structure with compact two-dimensional (2D), micro-granular, nanorod-shaped, and nano-fibrillar PANI layers from bottom to top. In addition, the possible formation mechanism of the lamellar structure of PANI film is discussed.

Two-dimensional plate-like PANI are successfully synthesized by a self-assembly process using benzoyl peroxide as oxidant. The micelles formed by aniline/p-TSA salt serves as ‘soft template’ to form PANI micro/nanostructures and proper [An]/[acid] ratios are required for the formation of plate-like PANI. It is found that at high [An]/[p-TSA] ratios (5:1 to 2:1) plate-like PANI are obtained, while at low [An]/[p-TSA] ratios ranging from 1:1 to 1:3 PANI nanoparticles are obtained. The influence of the other synthetic parameters, such as temperature, the concentration of benzoyl peroxide and stirring, on the morphologies of the PANI micro/nanostructures has also been investigated. Fourier transform infrared (FTIR), UV–vis spectroscopy (UV–vis), X-ray photoelectron spectroscopy (XPS), as well as X-ray diffraction (XRD) and cyclic voltammeter method (CV) are applied to characterize the products.

A facile route to prepare Fe3O4/polypyrrole (PPY) core-shell magnetic nanoparticles was developed. Fe3O4 nanoparticles were first prepared by a chemical co-precipitation method, and then Fe3O4/PPY coreshell magnetic composite nanoparticles were prepared by in-situ polymerization of pyrrole in the presence of Fe3O4 nanoparticles. The obtained nanoparticles were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and laser particle size analyzer. The images indicate that the size of Fe3O4 particles is about 10 nanometers, and the particles are completely covered by PPY. The Fe3O4/PPY core-shell magnetic composite nanoparticles are about 100 nanometers and there are several Fe3O4 particles in one composite nanoparticle. The yield of the composite nanoparticles was about 50%. The sedimentation behavior of Fe3O4/PPY core-shell magnetic nanoparticles in electrolyte and soluble polymer solutions was characterized. The experimental results indicate that the sedimentation of particles can be controlled by adjusting electrolyte concentration, solvable polymers and by applying a foreign field. This result is useful in preparing gradient materials and improving the stability of suspensions.

Polypyrrole (PPy) nanowire modified electrodes were prepared electrochemically by template-free method based on graphite electrodes. The freshly prepared electrodes were dipped in 10% HClO4 solution at least 24 h for removal of carbonate ions. The modified electrodes toward ascorbic acid were characterized by potentiostatic method. The experiment's results show that the PPy modified electrodes have obvious electrocatalytic effect toward ascorbic acid oxidation. The oxidation current density has a good linearity in the concentration range of 5.0 × 10−4 and 2.0 × 10−2 mol L−1 of ascorbic acid. The determination sensitivity may be significantly affected by the thickness of PPy film and pH of the test solution. The method has promising application in determination of ascorbic acid in the real samples.

Polypyrrole (PPy) nanowire modified electrode was prepared and its electrocatalytic behavior towards nitrate reduction was characterized. The electrode surfaces were investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The electrocatalytic activity of modified graphite electrode was compared with graphite, copper (Cu) and platinum (Pt) electrode. The nitrite concentration produced at PPy modified electrode is lower than that at any other electrodes, and its changing tendency is opposite to any other electrodes. The PPy nanowire modified electrodes were further modified by electrodeposition of Cu. The results show that the produced nitrite concentration gets higher with the increase of Cu content. The primary experimental results show that the modified electrode has promise use in the remove of nitrate from water.

In this paper, the electrochemical solid-phase extraction (EC-SPE) and amperometric determination of nitrite with polypyrrole (PPy) nanowire modified electrode was reported. The PPy nanowire modified electrode was prepared by template-free method in a mixture of sodium carbonate and sodium bicarbonate aqueous solution and then conditioned in 0.10 M perchlorate acid for 24 h. EC-SPE (preconcentration) of nitrite ions was conducted under the condition of applied potential 0.800 V for 300 s. The electroreduction of nitrite was conducted under the condition of −0.200 V for 100 s in the solution of 0.50 M H2SO4. The length of nanowires, the temperature and the pH of the test solution, the EC-SPE potential and time have significant effects on the corresponding current. Under a certain condition, the relationship between nitrite concentration and corresponding current density is in good linearity. The determination sensitivity may be varied according to the modification parameters. Under the experimental condition, the highest corresponding sensitivity is 55.84 mA/M cm2, and may be further improved by modification the electrode with longer polypyrrole nanowires.

In this paper, the electrochemical behavior of polypyrrole nanowire modified electrode is described. The modified electrode has very good activity toward nitrite electroreduction. The electroreduction current is linearly dependent on the concentration of nitrite. The experimental parameters such as thickness of polypyrrole film, pH, and temperature of the test solution, and scan rate which have effects on the reduction current were examined. The result shows that the electroreduction current increases with the increasing of the polypyrrole film thickness, acidity of electrolyte solution, temperature, and scan rate. The good linearity between the electroreduction current and the concentration of nitrite makes it possible to determine nitrite concentration accurately in the range of 2.28×10−4 to 0.020 M.

The behavior of the polypyrrole (PPy) fibrils modified electrode during hydrogen evolution process is reported. The experimental results show that the hydrogen evolution current density could be significantly increased on the PPy fibrils modified electrode. The hydrogen evolution current density on the modified electrode increases with PPy fibrils getting longer. The hydrogen evolution current density on fibrillar PPy modified electrode is higher than that on electrode modified with PPy with cauliflower form. Redoping PPy fibrils with metal complex could further increase the hydrogen evolution current density.

Polypyrrole nanowires growing with two-dimensional instantaneous nucleation and one-dimensional growth pattern were realized on graphite/paraffin composite electrode in phosphate buffer solution.