E. Subramanian

Solar energy in production of L-glutamate through visible light active photocatalyst-redox enzyme coupled bioreactor

A new potentially promising visible-light driven photobioreactor synthesizes fine chemical via photobiocatalysis by generating NADH in a non-enzymatic light-driven process and coupling it to the enzymatic dark reaction catalysis.

Conducting Polyaniline Blends with the Soft Template Poly(Vinyl Pyrrolidone) and their Chemosensor Application

This article reports the influence of poly(vinyl pyrrolidone) (PVP) soft-template without/with p-hydroxybenzoic acid (HBA) on the characteristics and chemosensor application of polyaniline (PANI). PANI and PANI-HBA have micrograins while the PANI-PVP blend exhibits nanostructure; the PANI-PVP-HBA blend has microgranules/microspheres. In sensor behavior, PANI shows greater sensitivity towards C6H5Cl and CH2Cl2 and less sensitivity to CHCl3. Contrarily, the PANI-PVP blend has improved sensitivity to CHCl3 but less to CH2Cl2. When PVP and HBA are present together, the resulting PANI materials lose their sensitivities. Thus, the soft-template role of PVP is operative only on blending it alone with PANI, but with HBA it gets modified/nullified.

Cross-Linked Poly(Vinyl Pyrrolidone) Hard-Template and Polymerization Method in Controlling Nanostructures and Properties of Polyaniline Composites

The present work investigates the use of hard template cross-linked poly(vinyl pyrrolidone) (CPVP) in polyaniline (PANI) material design. In chemical polymerization with slight modification in synthesis conditions, CPVP regulates the formation of three PANI composites PANI-CPVP 1 (nanorods) PANI-CPVP 2 (nano-rice-like structures) and PANI-CPVP 3 (crystalline grains). FTIR, XRD and SEM techniques explain the different chemical and structural modifications in the composites compared to PANI. In thermogravimetry, PANI has three-step weight-loss while PANI-CPVP composites exhibit 4/5 step weight-loss. All the composites exhibit characteristic differences in conductivity and hardness properties. An interrelationship thus exists between macromolecular nanostructures and properties.

Single/Double Soft-Templates Involved Synthesis of Polyaniline Blends: Interfacial Polymerization and Characterization by AC Impedance Analysis

Polyaniline (PANI) blends with single and double soft-templates (polyvinylpyrrolidone – PVP and/or sodium dodecylbenzenesulfonate – SDBS) were synthesized using interfacial polymerization. Fourier transform infrared (FTIR) spectral study confirmed blend formation. Polyaniline-polyvinylpyrrolidone (PANI-PVP) blend had submicron aggregates of 50–150 nm nanoparticles while PANI-SDBS blend had extensively agglomerated large size flakes/grains. Polyaniline-polyvinylpyrrolidone-sodium dodecylbenzenesulfonate (PANI-PVP-SDBS) blend had larger aggregates, besides significant number of smaller grains. Alternating current (AC) impedance analysis was performed to determine their electrical properties. At room temperature the AC conductivity of the blend materials was in the increasing order, PANI < PANI-PVP < PANI-SDBS < PANI-PVP-SDBS. But other parameters, like critical frequency and power law index s, exhibited a decreasing trend in the blend materials. With regard to frequency-dependence, all the materials showed constant AC conductivity at low frequencies, but at higher frequencies and at higher temperatures conductivity increased gradually. The obeyance of a universal power law and the range of s values (0.12 < s < 0.78) suggested a correlated barrier hopping (CBH) mechanism for AC conductivity of all the materials. The trends in electrical properties that were characteristic of the role of single/double soft-templates were explained in terms of improved π-electron delocalization and hopping mechanism.

Effect of anodization time on the growth of twinned pyramid crystals of bismite from polyhedral bismuth particle by facile electrolysis-based oxidation

ABSTRACT Nanostructured bismite films were fabricated by both thermal oxidation and electrochemical anodization of Bi film in NaOH aqueous electrolyte. Pure phase of α-bismite was obtained by the thermal oxidation technique. Pure-phase α and β bismites were successfully prepared by varying the anodization time. Truncated polyhedral aggregates of bismuth particles were converted to twinned pyramids particles having nanoscale tips with increase in anodization time. The crystallite size increased with anodization time from 43 nm to 79 nm. The band gap value lowered from 2.835(2) eV to 2.422(1) eV with anodization time and this is in agreement with the increase in crystallite size obtained from XRD. The shift in the absorption edge to higher wavelength with anodization time was attributed to the smoothening of surface and grain growth.

Electron beam induced structural transitions in polyaniline-dodecatungstophosphoric acid composite

Radiation induced chain scission and crosslinking lead to structural transformation in Polyaniline (PAni) whereas in the hybrid the degree of crystallinity increases on increasing dose rate. The formation of more delocalized polarons on electron irradiation is observed from the Raman studies.