Publications

In the present study, ionic polymer metal composite (IPMC) membrane actuator based on triple‐layered thorium(IV) phosphate/polyaniline/Pt (ThP‐PANI‐Pt) was prepared via consecutive solution recasting and electroless plating methods. The triple‐layered membrane is composed of thorium(IV) phosphate (ThP) inorganic cation exchanger layer in the middle section, two layers of polyaniline deposited through in situ polymerization and finally Pt electrode layers on both the surfaces on the outer section. The water uptake capacity of the ThP‐PANI composite polymer membrane was found to be 95.40% at 45ºC for 10 h of immersion time. The ion exchange capacity and proton conductivity was found to be 1.6 meq g −1 of dry membrane and 1.12 × 10 −3 S cm −1 , respectively. Maximum water loss from IPMC was 38% at 4 V for a time period of 12 min. Scanning electron micrographs shows the smooth and uniform coating of Pt on both side of composite polymer membrane surfaces. Cyclic voltammetry, linear sweep voltammetry, transmission electron microscopy, Fourier transforms infrared spectroscopy, thermal gravimetric analysis, X‐ray diffraction, and tip displacement of ThP‐PANI‐Pt IPMC membrane actuator was also examined. POLYM. ENG. SCI., 57:258–267, 2017. © 2016 Society of Plastics Engineers

We report on a new organic dye based on phenothiazine for DSC application.

The flexible soft actuators of conducting polymers can directly convert electrical stimulus into mechanical motions, which can be used for robotics and biomimetic applications. Herein, an electro-responsive membrane actuator based on poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate), functionalized single-walled carbon nanotube was fabricated using solution casting method with poly(vinyl alcohol) as a base intermediate polymer membrane. The poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) was evenly ornamented onto the single-walled carbon nanotube/poly(vinyl alcohol) membrane (single-walled carbon nanotube/ poly(vinyl alcohol)/ poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)) surfaces through dip coating and verified by scanning electron and transmission electron microscopy analysis. The desirable bending response of the fabricated single-walled carbon nanotube/ poly(vinyl alcohol)/poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) membrane with time at different voltages and generated tip force makes it a promising material as a new-generation conductive polymer-based soft actuator. A permutation of the electrical conductivity, more surface area, and admirable electromechanical properties of the single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) components consequences in the composite electrode exhibited excellent actuation performance compared to the ionic polymer-metal composite actuators with Pt electrodes surface. The fabricated actuator membrane can be employed for artificial muscles, robotics, and other bio-mimetic applications.

Abstract Amino‐functionalized zirconium‐based metal‐organic frameworks (MOFs) have shown unprecedented catalytic activity compared to non‐functionalized analogues for hydrolysis of organophosphonate‐based toxic chemicals. Importantly, the effect of the amino group on the catalytic activity is significantly higher in the case of UiO‐66‐NH 2 , where the amino groups reside near the node, compared to UiO‐67‐ m ‐NH 2 , where they are directed away from the node. Herein, we show that the proximity of the amino group is crucial for fast catalytic activity towards hydrolysis of organophosphonate‐based nerve agents. The generality of the observed amine‐proximity‐dictated catalytic activity has been tested on two different MOF systems which have different topology. DFT calculations reveal that amino groups on all the MOFs studied are not acting as Brønsted bases; instead they control the microsolvation environment at the Zr 6 ‐node active site and therefore increase the overall catalytic rates.

The conductance behavior of Zn2+ and Cu2+ and their complexes with two ligands (crown ethers) have been inspected in 10, 20, 30, and 40% DMF–water mixed solvent at 298.15, 308.15, 318.15, and 328.15 K. The conductance study indicates a 1 : 1 complexation mode amongst the metal ions and ligands hereby studied. The order of stability constants with crown ethers was found to be Cu(II) > Zn(II). The stability constant for Zn2+ ion with crown ether complexes in 10 and 40 wt % solvent composition varies in the order of benzo-18-crown-6 > benzo-15-crown-5. The stability constant for Cu2+ ion with crown ether complexes in 10% solvent composition varies in the order of benzo-18-crown-6 > benzo-15-crown-5, and for 40% solvent composition, it is benzo-18-crown-6 > benzo-15-crown-5. The enthalpy and the entropy of complexation were estimated from the variation of stability constants with respect to the variation of temperature. The observed results elicit that the complexation is enthalpy stabilized, but entropy destabilized.

A novel Ag-alumina hybrid surface-enhanced Raman spectroscopy (SERS) platform has been designed for the spectroscopic detection of surface reactions in the steady state. Single crystalline and faceted silver (Ag) nanoparticles with strong light scattering were prepared in large quantity, which enables their reproducible self-assembly into large scale monolayers of Raman sensor arrays by the Langmuir-Blodgett technique. The close packed sensor film contains high density of sub-nm gaps between sharp edges of Ag nanoparticles, which created large local electromagnetic fields that serve as "hot spots" for SERS enhancement. The SERS substrate was then coated with a thin layer of alumina by atomic layer deposition to prevent charge transfer between Ag and the reaction system. The photocatalytic water splitting reaction on a monolayer of anatase TiO2 nanoplates decorated with Pt co-catalyst nanoparticles was employed as a model reaction system. Reaction intermediates of water photo-oxidation were observed at the TiO2/solution interface under UV irradiation. The surface-enhanced Raman vibrations corresponding to peroxo, hydroperoxo and hydroxo surface intermediate species were observed on the TiO2 surface, suggesting that the photo-oxidation of water on these anatase TiO2 nanosheets may be initiated by a nucleophilic attack mechanism.

Herein, we investigated the impact of different additives [polyols (glucose, galactose, and maltose)/electrolytes (KCl, K2SO4, and K3PO4·7H2O)] on the interaction between quinolone antibiotic drug, ciprofloxacin hydrochloride (CFH), and Triton X-100 (TX-100) via the cloud point (CP) measurement technique. The magnitudes of CP of TX-100 were observed to be reduced with the enlargement of TX-100 concentration. The CP values show U-shaped variation as a function of CFH concentration in the aqueous medium. The CP values dwindle in the existence of electrolyte, which continues with the rise of electrolyte concentration. The observed CP values in the electrolyte medium follow the order CPK3PO4·7H2O > CPK2SO4 > CPKCl. The CP values reduced in the presence of organic additives (polyols) also. The executed magnitudes of Gibbs free energy (ΔGc°) of clouding were positive in all cases, signifying the nonspontaneous phenomenon. The ΔGc° values reduce with TX-100 concentration. The values of enthalpy of clouding (ΔHc°) and entropy of clouding (ΔSc°), as well as different transfer properties of thermodynamic parameters, were estimated and interpreted in detail. Excellent entropy–enthalpy compensation was observed in all cases.