Synthesis of pH‐ and solvent‐responsive smart core crosslinked star polymer by atom transfer radical polymerization

A highly fluorescent fluorescein dye labeled star shaped random copolymer with precise energy distribution was synthesized using atom transfer radical polymerization. The arm‐first strategy was utilized to achieve star architecture of the polymer. Dye labeling was carried out by azide‐alkyne cycloaddition. Acrylic acid and fluorescein dye both contributed to achieve a pH response. The synthesized polymer showed an attractive pH‐ and solvent‐sensitive fluorescence owing to efficient energy transfer from one fluorescent center to another. © 2014 Society of Chemical Industry     

Enhanced conversion efficiency of quasi solid state dye sensitized solar cells based on functionalized multi-walled carbon nanotubes incorporated TiO<Subscript>2</Subscript> photoanode

A series of quasi solid state dye sensitized solar cells were fabricated based on the different weight% of MWCNT@TiO₂ photoanode. The MWCNT@TiO₂ nanocomposites were synthesized by simple wet impregation method. The incorporation of MWCNT into the TiO₂ was confirmed by X-ray diffraction, energy dispersive X-ray spectrum and UV–visible spectroscopy. The morphological properties of the nanocomposites were analyzed by transmission electron microscopic analysis. The performance of the quasi solid state dye sensitized solar cell depends solely on the MWCNT content of the photoanode, as the same PVA polymer gel electrolyte has been used. Compared to the conventional TiO₂ photoanode based DSSCs 0.05 wt% MWCNT containing photoanode provide the maximum short circuit current density and the photo conversion efficiency of 9.811 mA/cm^?2 and 3.59 %. The introduction of MWCNT into the TiO₂ results in the rapid electron transport in the photoanode by forming a conductive network due to which improvement in the short circuit current was observed.     

Synthesis and evaluation of swelling kinetics of electric field responsive poly(vinyl alcohol)‐g‐polyacrylic acid/OMNT nanocomposite hydrogels

Novel electro‐responsive nanocomposite hydrogels were prepared by the radical graft polymerization reaction of partially neutralized acrylic acid on poly(vinyl alcohol) and organically modified MMT nanoclay (OMMT) using glutaraldehyde as a crosslinker and potassium initiator. The structures of the hydrogels were confirmed by using Fourier transform infrared, X‐ray diffraction, and scanning electron microscopy study. The nanocomposite hydrogels were characterized by evaluating such molecular weight between crosslinks, (Mc) crosslinking density (ρ), and mesh size (ξ). The effects of various parameters on the swelling behavior of the hydrogels were studied. The thermogravimetric analysis indicated that introduction of clay resulted in an increase in thermal stability. Finally, the electric stimuli responsive measurement indicates the bending of hydrogel toward the cathode in an aqueous solution of NaCl. POLYM. COMPOS., 36:34–41, 2015. © 2014 Society of Plastics Engineers     

Studies on Ag/Polypyrrole composite deposited on the surface of styrene-methyl acrylate copolymer microparticles and their electrical and electrochemical properties

The colloidal dispersion of silver nano particles with different concentration (0.5, 1.0 and 1.5%) were synthesized by chemical reduction method using citrate as reducing agent. Colloidal dispersion of Poly (Styrene-co-methylacrylate) (SMA) was synthesized by mini emulsion polymerization technique. The SMA micro particles were used as template for the polymerization of pyrrole in presence of dispersion of silver nano particles by oxidative coupling method. The Ag nano particles and the final core–shell composite particles were characterized by UV–visible, FTIR, SEM, EDX and TEM analysis. The thermal analysis revealed that the SMA-PPy-Ag core–shell particles possesses better thermal stability in comparision with bare PPy-Ag nano composite. The dc conductivity and the electro chemical behaviour of the particles were studied by using a standard four-probe method. The dependence of electrical conductivity of the composites on the concentration of silver in the polypyrrole shell and the methyl acrylate content in SMA copolymer were also investigated The core–shell particles show reversible electrochemical response as revealed by the cyclic voltammetry study.