Enhanced corrosion protection coatings prepared from soluble electronically conductive polypyrrole‐clay nanocomposite materials

Abstract

A series of electronically conductive nanocomposite materials that consisted of soluble polypyrrole (PPY) and layered montmorillonite (MMT) clay platelets were prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic PPY matrix via an in situ oxidative polymerization with dodecylbenzene sulfonic acid (DBSA) as dopant. Organic pyrrole monomers were first intercalated into the interlayer regions of organophilic clay hosts and followed by a one-step oxidative polymerization. The as-synthesized electronically conductive polypyrroleclay nanocomposite (PCN) materials were then characterized by Fourier transformation infrared (FTIR) spectroscopy, wide-angle powder X-ray diffraction (XRD), and transmission electron microscopy (TEM). PCNs in the form of coatings with low clay loading (e.g., 1.0 wt %) on cold-rolled steel (CRS) were found to exhibit much better in corrosion protection over those of pristine PPY based on a series of electrochemical measurements including corrosion potential, polarization resistance, and corrosion current in 5 wt % aqueous NaCl electrolyte. Effects of the material composition on the thermal stability, optical properties, and electrical conductivity of pristine PPY along with PCN materials, in the form of fine powder, powder-pressed pellet, and solution, were also studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), UV-visible absorption spectra, and four-point probe technique, respectively. The viscosity of PPY existed in PCN materials and pristine PPY were determined by viscometric analysis with m-cresol as solvent. The heterogeneous nucleating effect of MMT clay platelets in PPY matrix was studied by wideangle powder XRD. The corresponding morphological images of the nucleating behavior of clay platelets in PPY matrix were investigated by scanning electron microscopy (SEM).

Effect of organoclay on the thermal stability, mechanical strength, and surface wettability of injection‐molded ABS–clay nanocomposite materials prepared by melt intercalation

“…According to the published reports on PCN materials, the unparalleled ability of smectite clays was found to boost the thermal stability of polymers. 1,[5][6][7][8][9][10][11][12][13][14][15][16] Evidently, we found that the onset of the thermal decomposition of those PCN materials shifted slightly toward higher temperature range than that of neat ABS, which confirmed the enhancement of intercalated polymers. After ϳ700°C, the curves are all leveled off, and mainly the inorganic residue (e.g., Figure 1 The representative FTIR spectra of (a) neat ABS (b) CLABS1 (c) CLABS3 (d) CLABS5 (e) organophilic clay (f) Na ϩ -clay.…”

“…Generally, they combine both the characteristics of the inorganic material and the organic polymer. PCN material is a promising system because the clay possess a high aspect ratio and a platy morphology and can be employed to boost the physical properties (e.g., thermal stability, 1 mechanical strength, 2 fire retardant, 3 gas barrier, 4 and corrosion protection [5][6][7][8][9][10][11][12][13][14][15][16] ) of bulk polymers.…”

Double corrosion protection mechanism of molybdate-doped polypyrrole/montmorillonite nanocomposites

“…It is known that MMT plays as a good barrier to prevent corrosive species due to the layer structure [8,9,[19][20][21][22]. So MMT will have the same effects for all the samples.…”

“…As a result, corrosion rate decreases. In addition, MMT played a role as a barrier to prevent the corrosive species from steel [8,9,[19][20][21][22]. Consequently, metal should be protected with two effects at the same time, say anion inhibitor and barrier.…”

“…During protection time, PPy was reduced and these dopants were released from PPy to heal the corrosion defect. So, the mobility of dopant anion played an important role for the self-healing effect [2,8,9].…”