A series of nanocomposite materials that consisted of emeraldine base of polyaniline and
layered montmorillonite (MMT) clay were prepared by effectively dispersing the inorganic
nanolayers of MMT clay in organic polyaniline matrix via in-situ polymerization. Organic
aniline monomers were first intercalated into the interlayer regions of organophilic clay
hosts and followed by an one-step oxidative polymerization. The as-synthesized polyaniline−clay lamellar nanocomposite materials were characterized by infrared spectroscopy, wide-angle powder X-ray diffraction, and transmission electron microscopy. Polyaniline−clay
nanocomposites (PCN) in the form of coatings with low clay loading (e.g., 0.75 wt %) on
cold-rolled steel (CRS) were found much superior in corrosion protection over those of
conventional polyaniline based on a series of electrochemical measurements of corrosion
potential, polarization resistance, and corrosion current in 5 wt % aqueous NaCl electrolyte.
The molecular weights of polyaniline extracted from PCN materials and bulk polyaniline
were determined by gel permeation chromatography (GPC). Effects of the material
composition on the gas barrier property, thermal stability, and mechanical strength of
polyaniline along with PCN materials, in the form of both fine powder and free-standing
film, were also studied by gas permeability measurements, differential scanning calorimetry,
thermogravimetric analysis, and dynamic mechanical analysis.
A series of polymer-clay nanocomposite (PCN) materials that consisted of poly(methyl methacrylate) (PMMA) and layered montmorillonite (MMT) clay were prepared by effectively dispersing the inorganic nanolayers of MMT clay in an organic PMMA matrix via in situ thermal polymerization. Organic methyl methacrylate monomers were first intercalated into the interlayer regions of organophilic clay hosts followed by a typical free radical polymerization. The as-synthesized PCN materials were characterized by infrared spectroscopy, wideangle powder X-ray diffraction, and transmission electron microscopy. PCN coatings with low clay loading (e.g., 1 wt %) on cold-rolled steel were found much superior in anticorrosion over those of bulk PMMA based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current, and impedance spectroscopy in 5 wt % aqueous NaCl electrolyte. The molecular weights of PMMA extracted from PCN materials and bulk PMMA were determined by gel permeation chromatography with tetrahydrofuran as an eluant. Effects of the material composition on the molecular barrier, optical clarity, and thermal stability of PMMA along with PCN materials, in the form of both free-standing film and fine powder, were also studied by molecular permeability analysis, ultravioletvisible transmission spectra, differential scanning calorimetry, and thermogravimetric analysis, respectively.
ABSTRACT:A series of polymer-clay nanocomposite (PCN) materials consisting of organic poly(methyl methacrylate) (PMMA) and inorganic montmorillonite (MMT) clay platelets were prepared successfully by the effective dispersion of nanolayers of the MMT clay in the PMMA framework through both in situ emulsion polymerization and solution dispersion. The as-prepared PCN materials obtained with both approaches were subsequently characterized with wide-angle powder X-ray diffraction and transmission electron microscopy. For a comparison of the anticorrosion performance, a PCN material (e.g., 3 wt % clay loading) prepared by in situ emulsion polymerization, showing better dispersion of the clay platelets in the polymer matrix, exhibited better corrosion protection in the form of a coating on a cold-rolled steel coupon than that prepared by solution dispersion, which showed a poor dispersion of the clay nanolayers according to a series of electrochemical corrosion measurements. Comparative studies of the optical clarity, molecular barrier properties, and thermal stability of samples prepared in both ways, as membranes and fine powders, were also performed with ultraviolet-visible transmission spectroscopy, molecular permeability analysis, thermogravimetric analysis, and differential scanning calorimetry.
An organic/inorganic hybrid nanocomposite membrane, poly(vinyl alcohol)/clay (PVAC), was prepared. The morphology of PVAC nanocomposite membranes were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The crystallinity and surface roughness increases with an increasing clay content in the PVAC nanocomposite membrane. Compared with the pure poly(vinyl alcohol) (PVA) membrane, the hybrid nanocomposite membrane (PVAC) shows an improvement in the thermal stability and the prevention of the water-soluble property. The oxygen permeability and the water-vapor permeation rate decreases with an increasing clay content (1-3 wt %) in the PVAC nanocomposite membranes. In addition, the effects of the clay content on the vapor-permeation performance of an aqueous ethanol solution through the PVAC nanocomposite membranes was also investigated.
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