Tsao-Cheng Huang

Synergistic effect of electroactivity and hydrophobicity on the anticorrosion property of room-temperature-cured epoxy coatings with multi-scale structures mimicking the surface of Xanthosoma sagittifolium leaf†

A novel method is introduced to fabricate an electroactive epoxy (EE) coating with structured hydrophobic surfaces using an environmentally friendly process for anticorrosion application. First of all, the electroactive amine-capped aniline trimer (ACAT) was used as a curing agent to cure the epoxy resin and additionally provided electroactivity to the cured epoxy resin. The EE coating was cured at room temperature without using any solvent. The increased amount of the ACAT component in the EE coating not only accelerated the curing process but also promoted the thermal stability and anticorrosion performance. Subsequently, the multi-scale papilla-like structures on the surface of the Xanthosoma sagittifolium leaf were successfully replicated on the surface of the EE coating using PDMS as a negative template, as evidenced by the SEM investigation. The resulting hydrophobic electroactive epoxy (HEE) coating with the replicated nanostructured surface showed a hydrophobic characteristic with a water contact angle close to 120°. The developed HEE coating exhibited superior anticorrosion performance in electrochemical corrosion tests as its corrosion rate is better than that of the bare steel substrate by a factor of 450. The significantly improved corrosion protection is attributed to, besides the steel substrate isolated by the coating, the synergistic effect of electroactivity and hydrophobicity from the HEE coatings with the multi-scale structures mimicking the surface of the Xanthosoma sagittifolium leaf.

Electrochemical investigations on anticorrosive and electrochromic properties of electroactive polyurea

In this study, electrochemical investigation of corrosion protection and electrochromic properties of aniline-pentamer-based electroactive polyurea (EPU) coating prepared by oxidative coupling polymerization is presented. Monitoring of the in situ chemical oxidation process for the reduced form of soluble EPU in N-methyl-2-pyrrolidone (NMP) by the incorporation of an oxidant was performed by measuring UV-Visible absorption spectra. Moreover, the electroactivity of EPU was evaluated by performing electrochemical cyclic voltammetry (CV) studies. The EPU coating was found to exhibit enhanced corrosion protection effect on cold-rolled steel (CRS) electrodes as compared to a corresponding non-electroactive polyurea (NEPU) coating based on a series of electrochemical measurements in 3.5 wt% NaCl electrolyte. The electrochromic performance of EPU was investigated by measuring electrochromic photographs and UV absorption spectra.

The use of a carbon paste electrode mixed with multiwalled carbon nanotube/electroactive polyimide composites as an electrode for sensing ascorbic acid

Carbon paste electrodes (CPEs) modified by the addition of amino-functionalized multiwalled carbon nanotube/electroactive polyimide (AF–MWCNT/EPI) composites (AF–MWCNT/EPI-CPE) have been prepared and applied to the electrochemical sensing of ascorbic acid (AA). First, MWCNTs were grafted with 4-aminobenzoic acid in a medium of polyphosphoric acid/phosphorus pentoxide to obtain MWCNTs functionalized with 4-aminobenzoyl groups (AF–MWCNTs). The amino functional groups on the AF–MWCNTs reacted with an oligoaniline by oxidative coupling polymerization to yield the AF–MWCNT/EPI composites. Fourier transform infrared spectra and Ultraviolet-Visible absorption spectra revealed that the quinoid rings present on the EPI graft interacted with the AF–MWCNTs. Cyclic voltammetry studies indicated improved electrochemical properties of the AF–MWCNT/EPI composites, demonstrating the occurrence of efficient electron/charge transfer between the AF–MWCNTs and the EPI graft. The concentration of the added AA and the change in the peak current obtained showed a linear relationship. In addition, the calibration curve of the amperometric response of the AF–MWCNT/EPI-CPE sensors against the concentration of AA was also linear. The detection limit and the sensitivity of the AF–MWCNT/EPI-CPE AA sensors were 4.1 μM at a S/N (signal to noise ratio) of 3 and 27.5 μA mM−1, respectively.

Photoactively electroactive polyamide with azo group in the main chain via oxidative coupling polymerization

In this work, a simultaneously photoactive and electroactive polyamide exhibiting interesting spectroscopic and electrochemical properties was prepared. Firstly, a 4-aminoazobenzene-capped amide oligomer (ACAO) was synthesized and characterized by 1H NMR, 13C NMR and mass spectroscopy. Subsequently, the photoactively electroactive polyamide was synthesized through reacting ACAO with p-phenylenediamine by oxidative coupling polymerization, followed by characterization with GPC and 1H NMR. After alternate irradiation with UV and visible light, the azobenzene exhibited obvious photoelectrochemical switching properties. The reversible photoisomerization (i.e., cis ↔ trans) behaviour of the backbone azobenzene moieties in the as-prepared photoactively electroactive polyamide was analyzed by in situ monitoring through systematic studies of UV-visible and 1H NMR spectroscopies. On the other hand, the electrochemical activity (i.e., redox capability) of the as-prepared polyamide was explored by cyclic voltammetry (CV) measurements.

Synthesis and electroactive properties of poly(amidoamine) dendrimers with an aniline pentamer shell

Poly(amidoamine) (PAMAM) dendrimers with different generations (G = 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 πB–πQ 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.

Advanced superhydrophobic electroactive fluorinated polyimide and its application in anticorrosion coating

ABSTRACT A novel superhydrophobicelectroactive fluorinated polyimide (HEFPI) was first synthesized from aniline trimer and 4,4′-(Hexafluoroisopropylidene) diphthalic anhydride. The HEFPI could be fabricated as superhydrophobicfilm by replicated the surface of the Xanthosomasagittifolium leaves. The water contact angle of HEFPI film reaches as high as 157 ° and the superhydrophobic property of HEFPI could coat on cold-rolled steel (CRS) to prevent the metal corrosion. Electroactivity of EFPI was evaluated by performing electrochemical cyclic voltammetry study. Besides, redox catalytic capabilities of aniline trimer units existed in HEFPI main chain may induce the formation of passive metal oxide layers on the CRS electrode. The synergistic effects (hydrophobic property and passive metal oxide layers) make the HEFPI coating has great potential for advanced anticorrosion material.

Electroactive polyamide modified carbon paste electrode for the determination of ascorbic acid

ABSTRACTS Construction electroactive polyamide (EPA) with aniline-pentamer-based in the main chain has been modified on the surface of carbon paste electrode (CPE) for detecting ascorbic acid (AA). Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy studies confirm the well-defined molecular structure of the oligoaniline and EPA. Further, the in situ chemical oxidation of EPA was monitored by UV-Visible absorption spectrum. The electroactivity of the EPA was evaluated by performing electrochemical cyclic voltammetry study. The sensing response studies have revealed that this EPA-modified CPE electrode can detect AA in the range of 0.05–0.7 mM with detection limit of 0.005 mM and sensitivity of 1.5 × 10–5 AmM–1. Besides, this EPA-modified CPE electrode shows a minimal relative standard deviation of 1.73%.

Polymer nanocomposite coatings

Abstract: This chapter discusses the properties of coatings made of polymer nanocomposites based on non-conductive polymers, electroactive polymers and conductive polymers. Anticorrosion resistance and tribology can be efficiently improved when nanoclay or nanoparticles are embedded in the polymer. Polymer nanocomposites made with carbon nanotubes have electrical properties and act as electromagnetic interference shielding. Some coating technologies suitable for polymer nanocomposites are discussed.