Rupali Gangopadhyay

How does PEDOT combine with PSS? Insights from structural studies

The severely intractable polymer poly(3,4-ethylenediethoxythiophene) (PEDOT) is brought to stable aqueous solution after in situ combination with polystyrene sulfonic acid (PSS). This solution (PEDOT–PSS) is stable and successfully combines the optical and electrical properties of PEDOT with the water solubility of PSS. This paper explores the physical properties of PEDOT–PSS from morphological and structural aspects and electronic structure studies are employed to understand the interaction between the two polymers. The solution consists of triangular/rectangular shaped nanoparticles and UV-vis spectroscopy is used to establish the highly doped and conductive nature of the sample with bipolarons present as carrier. Theoretical studies reveal the structure of the interpolymer complex and that the PEDOT chain is bent towards the PSS moiety, and thus, PEDOT–PSS is likely to form a partially coiled or helical structure. The unique stability of this system as well as its highly conductive nature is also consistent with the molecular model.

Effect of conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) nanotubes on electro-optical and dielectric properties of a ferroelectric liquid crystal

Abstract.A detailed comparative study of the dielectric and electro-optical properties of a ferroelectric liquid crystal (FLC) and FLC after having doped with conducting polymer Poly (3,4-ethylenedioxythiophene) (PEDOT) nanotubes is done. The electro-optic study reveals a lower electrical response time, rotational viscosity and spontaneous polarization in the FLC/PEDOT nanocomposite system. By fitting the capacitance with voltage in a Preisach model, four dipolar species in both FLC and composites system have been obtained. The orientation of the four dipolar species in the composites system is such that the effective dipole moment in the transverse direction of the FLC molecule is less than that in FLC compound.

Effects of conducting polymer poly(3, 4-ethylenedioxythiophene) nanotubes on the electro-optical and dielectric properties of a nematic liquid crystal 4-n-pentyl-4′-cyanobiphenyl host

We report the results of the optical transmission and the capacitance behavior as a function dc electric field of a pristine liquid crystal and conducting polymer nanotube-liquid crystal composite measured in twisted nematic cells. The threshold and driving voltages have been determined from transmission-voltage curve. There is remarkable reduction in the threshold and driving voltage in the polymer nanotube doped liquid crystal cell which is good from application point of view. The residual dc is also reduced significantly in the doped cell and the reduction is even more than that observed in the carbon nanotube doped same liquid crystal system.

A Comparative Study of Poly (3,4-ethylenedioxythiophene) (PEDOT) Nanotubes Doped Nematic Liquid Crystal (NLC) System and Carbon Nanotubes (CNT) Doped NLC System for Greater Modification of Electro-Optical Properties of the Host NLC 1770-2

The aim of this present paper is to compare the effects of conducting polymer, poly (3,4-ethylenedioxythiophene) nanotubes and carbon nanotubes, on the electro-optical properties of a nematic liquid crystal mixture (1770-2). From the optical transmission and capacitance behavior it has been proved that the conducting polymer – nematic liquid crystal system possesses much lower threshold voltage and driving voltage than the carbon nanotube – nematic liquid crystal system which might be very useful in display applications. The effective elastic constant has been also significantly reduced in the conducting polymer – nematic liquid crystal system.

Self-assembled PEDOT nanoropes: Materials for improving electro optical properties of liquid crystal

ABSTRACT A ropelike conducting polymer nanostructure was synthesized in this work. 3,4-ethylenedioxythiophene (EDOT) was polymerized in presence of a nematic liquid crystal (5CB) giving rise to the PEDOT nanoropes with diameter 10–20 nm. UV–Vis spectra of the nanoropes was comparable with the lightly doped bulk PEDOT. However, unlike the bulk polymer, the nanoropes or helical nanofibres, separated from the medium could be re-dispersed in chloroform and could be blended with 5CB. Electro optical properties of 5CB were remarkably modified after incorporation of PEDOT nanoropes. The residual current for optical transmission, threshold voltage for Freedericksz transition and capacitance hysteresis of 5CB were substantially lowered after nanorope incorporation.

Enhanced photoluminescence from gold nanoparticle decorated polyaniline nanowire bundles

Enhanced emission is observed from a nanocomposite consisting of conducting polyaniline nanowire bundles decorated with gold nanoparticles synthesized by simple physical blending and in situ interfacial polymerization techniques. Structural investigations revealed that both the methods led to the formation of nanocrystalline gold particles dispersed in a crystalline polyaniline nanowire matrix but the interfacial method leads to a better dispersion of the nanoparticles. Spectroscopic signatures suggest a strong electronic interaction between conducting polyaniline and gold that is manifested by a drastic modification of the plasmon absorption band of gold nanoparticles along with a significant enhancement in the emission characteristics. We, therefore, have a luminescent solid state material composed of gold and a conducting polymer which can find a huge range of applications based on suitable tailoring of the electrical and optical properties.

Stabilization of Conducting Polymers with CMC: Rheological Approach

Polyaniline (PAn) and Polypyrrole (PPy) were stabilized in aqueous medium using carboxy methyl cellulose (CMC) as an efficient steric stabilizer. Both these dispersions were stable for few days and have shown different rheological responses. PAn‐CMC resembles to a semidilute polymer solution while PPy‐CMC resembles to a reversible polymer network. After few days PPy‐CMC formed a soft gel that hardened gradually in course of time.