Mukul Biswas

Recent Progress in Synthesis and Evaluation of Polymer-Montmorillonite Nanocomposites

The review aims at highlighting the significant developments in the field of polymer-montmorillonite clay based nanocomposites with specific focus on synthetic methodologies used, characterization, and evaluation of relevant bulk properties of these composites.

Water-dispersible conducting nanocomposites of polyaniline and poly(N-vinylcarbazole) with nanodimensional zirconium dioxide

Abstract Water-dispersible composites of polyaniline (PANI) and poly( N -vinylcarbazole) (PNVC) with nanodimensional ZrO 2 were prepared. The incorporation of the polymers in the composites was endorsed by FTIR studies. SEM analyses revealed distinct morphological features of the composites. TEM analyses confirmed the particle sizes to be in the 300–500 nm range for PNVC–ZrO 2 and in the 250–300 nm range for the PANI–ZrO 2 composites, respectively. TG analyses revealed the enhanced stabilities of the nanocomposites relative to the base polymers. DC conductivities of the PNVC–ZrO 2 composites were in the order of (1–1.5)×10 −5 S/cm, which were 10 7 –10 10 -fold improved relative to the base polymer. The same for the PANI–ZrO 2 composite were in the range of (0.03–0.35)×10 −2 S/cm values increasing with increasing polymer loading in the composites.

Water dispersible conducting nanocomposites of poly(N-vinylcarbazole), polypyrrole and polyaniline with nanodimensional manganese (IV) oxide

Water dispersible composites of poly(N-vinylcarbazole) (PNVC), polypyrrole (PPY) and polyaniline (PANI) with colloidal MnO2 were prepared. The incorporation of the polymers in the composites was endorsed by FTIR studies. SEM analyses revealed distinct morphological features of the composites. TEM analyses confirmed particle sizes to be in the nanometer range. DC conductivities of the PNVC–MnO2 composites were 107 to 1010 fold improved relative to the base polymer while those for PPY–MnO2 or PANI–MnO2 composites increased with the increasing polymer loading and dopant amount.

Preparation and evaluation of composites from montmorillonite and some heterocyclic polymers: 3. a water dispersible nanocomposite from pyrrole-montmorillonite polymerization system

Montmorillonite (MMT)-based nanocomposites of polypyrrole (PPY) were prepared through the polymerization of pyrrole with MMT and FeCl3-impregnated MMT in bulk and in aqueous medium. The composites were characterized by IR, X-ray diffraction (XRD), and scanning electron microscopy (SEM) studies. XRD analyses revealed no change in d001 spacing in MMT (9.8 A), suggesting no intercalation of PPY into MMT lamellae. TEM analysis indicated the particle size to be 25 ± 7 nm. The bulk conductivity of the composites was in the range of (1.3 to 26) × 10−5 S/cm, depending on the FeCl3-impregnation level and on the PPY loading in the composites. Suitable procedures were developed for obtaining a stable aqueous dispersion and a reversible dispersion of these composites.

Water-dispersible nanocomposites of polyaniline and montmorillonite

The polymerization of aniline (ANI) in aqueous medium in the presence of (NH4)2S2O8 and montmorillonite (MMT) resulted in the formation of a nanocomposite (PANI–MMT). The inclusion of PANI in the composite was confirmed by FTIR studies. The extent of PANI loading in the composite increased with ANI concentration at a fixed oxidant/MMT amount and with the oxidant amount at a fixed ANI and MMT weight, but decreased with an MMT amount at a fixed ANI and oxidant level. TGA revealed a higher stability for the PANI–MMT composite relative to PANI and confirmed a PANI loading of ca. 51% in the composite. The conductivity increased in all the cases. XRD analysis revealed no expansion of the d001 spacing at 9.8 A, implying no intercalation of PANI within the MMT layers. Scanning electron micrography studies revealed interesting morphological features for the composites. Transmission electron micrography analysis revealed distinctive features and confirmed the formation of PANI–MMT composite particles of diameters in the 300- to 400-nm range. These composites could be obtained as stable colloids in the presence of poly (N-vinyl pyrrolidone) under selective conditions.

Preparation and evaluation of composites from montmorillonite and some heterocyclic polymers. II. A nanocomposite from N-vinylcarbazole and ferric chloride-impregnated montmorillonite polymerization system

The polymerization of N-vinylcarbazole in the presence of FeCl3-impregnated montmorillonite resulted in the formation of a poly(N-vinylcarbazole)–montmorillonite composite. XRD analysis of the composite revealed no expansion for d001 spacing, in sharp contrast to that for the same composite prepared in the absence of FeCl3. This indicated that the poly(N-vinylcarbazole) was not intercalated in the montmorillonite lamellae but was glued to it in the same way as was polypyrrole in colloidal silica, zirconia, or tin oxide nanocomposite systems. TEM analysis revealed the particle size of the composite to be in the range 30–40 nm. The dc conductivity of the poly(N-vinylcarbazole)–montmorillonite composite was in the range (3–5) × 10−5 S/cm depending upon the FeCl3 loading of montmorillonite.

A Colloidal Silica Poly(N-Vinylcarbazole) Nanocomposite Dispersible in Aqueous and Nonaqueous Media

Abstract N- vinylcarbazole was polymerized in the presence of FeCl 3 -impregnated ultrafine silica powder in benzene solution. The precipitation of polymer followed by benzene extraction of the poly( N- vinylcarbazole)-silica mass afforded a poly( N- vinylcarbazole)-silica nanocomposite. The composite exhibited a higher thermal stability and higher dc conductivity relative to poly( N- vinylcarbazole) homopolymer. Transmission electron microscopy analysis confirmed the particle size of the composite to be about 26 ± 5 nm. The nanocomposite could be dispersed in water, dimethyl sulfoxide, or propanol in the presence of polyvinylpyrrollidone to yield a stable suspension.

Conducting Composites of Polymethylmethacrylate with Acetylene Black

ABSTRACT Conducting composites of polymethylmethacrylate and acetylene black were prepared via potassium chromate–sodium arsenite initiated redox polymerization of methylmethacrylate in presence of a suspension of acetylene black in aqueous methanol medium at 60°C. Prolonged extraction of the composite by tetrahydrofuran failed to extract the polymethylmethacrylate completely from the acetylene black surface, as confirmed by Fourier Transform Infrared studies. Scanning electron microscopic analyses revealed the formation of agglomerates of particles of nonuniform sizes and shapes. Thermal stability of the composite was appreciably improved relative to that for the unmodified base polymer. In sharp contrast to the d.c. conductivity of polymethylmethacrylate homopolymer (10−13 S/cm), the conductivity of the composites reached values between 10−4 S/cm to 10−2 S/cm corresponding to acetylene black loading of 7% to 25%.

Catalytic Intervention of MoO3 toward Ethanol Oxidation on PtPd Nanoparticles Decorated MoO3–Polypyrrole Composite Support

Ethanol oxidation reaction has been studied in acidic environment over PtPd nanoparticles (NPs) grown on the molybdenum oxide-polypyrrole composite (MOPC) support. The attempt was focused on using reduced Pt loading on non-carbon support for direct ethanol fuel cell (DEFC) operated with proton exchange membrane (PEM). As revealed in SEM study, a molybdenum oxide network exists in polypyrrole caging and the presence of metal NPs over the composite matrix is confirmed by TEM analysis. Further physicochemical characterizations such as XRD, EDAX, and XPS are followed in order to understand the surface morphology and composition of the hybrid structure. Electrochemical techniques such as voltammetry, choroamperometry, and impedance spectroscopy along with performance testing of an in-house-fabricated fuel cell are carried out to evaluate the catalytic activity of the materials for DEFC. The reaction products are estimated by ion chromatographic analysis. Considering the results obtained from the above characterization procedures, the best catalytic performance is exhibited by the Pt-Pd (1:1) on MOPC support. A clear intervention of the molybdenum oxide network is strongly advocated in the EOR sequence which increases the propensity of the reaction by making the metallites more energy efficient in terms of harnessing sufficient numbers of electrons than with the carbon support.