Gursel Sonmez

Polymeric electrochromics for data storage

Three types of memory devices based on electrochromic polymers are prepared that use variations in optical density in dual type EC devices. In these devices, conducting electrochromic polymers act as the active layer and data is stored by using: (1) high contrast ratio between the oxidized and neutral states of the polymer, (2) different intensities of absorptions at different oxidation levels of polymer and (3) a mixture of any two additive primary colours (red, green and blue) in various oxidation levels.

Completion of the three primary colours: the final step toward plastic displays

A completion of the three primary colours (red, green and blue (RGB)) in conjugated polymeric electrochromics is enough to produce any shade of desired colour for plastic displays. Until our first report about a green-coloured neutral conjugated polymer (CP) [G. Sonmez, C. K. F. Shen, Y. Rubin and F. Wudl, Angew. Chem., Int. Ed. Engl., 2004, 43, 1498; G. Sonmez, H. B. Sonmez, C. K. F. Shen, R. W. Jost, Y. Rubin and F. Wudl, Macromolecules, 2005, in press; G. Sonmez, H. B. Sonmez, C. K. F. Shen and F. Wudl, Adv. Mater., 2004, 16, 1905; refs. ], researches on CPs as electrochromics have mainly focused on red and blue colours. In this article we describe the advantages of CPs as electrochromics and the importance of having RGB colours in polymeric electrochromic devices.

In situ colorimetric analysis of electrochromic polymer films and devices

Here we present an overview of an in situ method of electrochromic polymer characterization based on the CIE system of colorimetry. As illustrated here for PBuDOP (poly(3,4-butylenedioxypyrrole)), colorimetric analysis allows for precise understanding of color change and the accessible color states of an electrochromic polymer. This technique has proven to be a convenient method for the design and construction of electrochromic devices and promises to reduce trial and error in device construction while allowing for the fine-tuning and reproducibility of color.

Structural Study of Pyrrole-EDOT Copolymers on Carbon Fiber Micro-Electrodes

Copolymer films of pyrrole and 3,4-ethylenedioxythiophene (EDOT) were synthesized electrochemically on the carbon fiber microelectrodes (CFME). Deposition conditions on the carbon fiber and influence of the monomer concentrations to the copolymerization as well as the electrochemistry of the resulting polymers and copolymers were studied using cyclic voltammetry, in-situ spectroelectrochemistry, FTIR-ATR and scanning electron microscopy. Effect of the monomer ratio on the formation of the copolymer was reported. The electroactivity and very well defined electrochemistry of both polymers polypyrrole and PEDOT, and copolymer of pyrrole and EDOT on the CFME as much as the Pt electrode pioneers the possibility of using these coated electrodes for bio-applications. A high level of stability to overoxidation has also been observed for PEDOT as the polymer on the CFME substrate show limited degredation of their electroactivity at potentials 1.2 V above its half-wave potential.

Electrochemical polymerization of pyrrole in acrylamide solution

Abstract Electrochemical polymerization of pyrrole (Py) in an excess of acrylamide (AAm) was accomplished by using an acetonitrile–tetraethyl ammonium perchlorate (TEAPC) solution containing both monomers. Characterization of soluble and insoluble products was carried out via FT-IR spectrum, cyclic voltammogram (CV), UV–visible spectrum, scanning electron microscope (SEM), differential scanning calorimetry (DSC) and elemental analysis. The role of monomer concentrations on the formation of resulting polymer was investigated. Since the polymerization rate of Py is faster than that of AAm, the appropriate ratio of concentrations of monomers have chosen to have chance to interact AAm with Py oligomers which was formed immediately on the electrode surface. Inclusion of AAm to polymer and the mole ratio of resulting product was reported.

Acidity and electronegativity enhancement of C60 derivatives through cyano groups

We report the synthesis, characterization and physical properties of cyano and hydrocyano C60 derivatives. Electrochemical studies using differential pulse voltammetry (DPV) have shown that cyano groups on C60 increase the reduction potential and acidity of the proton on C60. It was shown that the reduction peak of C60(CN)4 is 280 mV more positive than the corresponding C60 peak. It was also found that C60H(CN)3 is highly acidic. This compound was estimated to be a stronger acid than dichloroacetic acid.

Water-soluble polypyrroles by matrix polymerization : Interpolymer complexes

A new class of water-soluble polypyrroles (PPy) has been developed. This was accomplished by oxidative matrix polymerization of pyrrole (Py) monomer with Ce(IV) in the presence of poly(acrylic acid (PAA), poly(vinyl pyrrolidone) (PVP), and copolymers (CP) of vinyl pyrrolidone(VP) with acrylic acid (AA) [VP/AA; 25/75 ( CP 1 ), 50/50 ( CP 2 ), 75/25 ( CP 3 )]. The soluble and insoluble interpolymer complexes were observed according to the nature ( and conformation ) of polymers in mixture, the ratio of components, and the pH of solutions. The role of PAA, PVP, CP, Py, and Ce(IV) concentrations, the order of component addition, and the pH of the solutions were investigated. The evidence and structural reasons for the formation of soluble interpolymer complexes of PPy with different polymers are discussed. It is proposed that the compactization of the polymer matrix as well as the disturbance of the regularity of reactive groups on the polymer chain decreases the possibility of formation of soluble interpolymer complexes.

In situ spectroelectrochemistry and colorimetry of poly(pyrrole-acrylamide)s

Electropolymerization of pyrrole in the presence and absence of acrylamide was accomplished. Characterization of the soluble and insoluble products was carried out by using UV-visible and FTIR spectroscopy, cyclic voltammetry, colorimetry and four-point probe technique. Role of applied electrical conditions and effect of the presence of acrylamide on the formation of polymers in the solution and on electrode surface were investigated. Conductivity of polypyrrole and poly(pyrrole-acrylamide) free-standing films show a conductivity of 90 and 1.0 S/cm, respectively. Incorporation of the acrylamide to the resulting polymer was supported by electrochemistry, colorimetric and spectroscopic results. The presence of the acrylamide in the resulting polymer affects some of the properties of the polymer film (i.e., color, conductivity, electrochemistry, spectroelectrochemistry, etc.) that may bring some advantages for practical applications.

Interaction of metal ions with polypyrrole on polyacrylic acid matrix

The oxidative matrix polymerization of pyrrole (Py) by Fe(III), Cu(II), Ni(II), Co(II), and Zn(II) in the presence of polyacrylic acid (PAA) was studied and water-soluble products along with insoluble products were obtained. The metal (Me) content of the insoluble part was determined by using atomic absorption spectroscopy (AAS). The effects of the oxidation potential of Me ions and ligands on the aggregation of polypyrrole (PPy) on the matrix polymer were measured by ultraviolet (UV)-visible spectra. These findings also were checked by cyclic voltammetry (CV) measurements on PAA–Cu and PAA–PPy–Cu interactions. The conductometric titration results of PAA–PPy–Me ternary solutions were explained in the light of the interaction of Me ions with Py to polymerize on the PAA matrix resulting in some free carboxyl groups with a possibility of having Me–polymer complexes and a ternary complex (PAA–Me–PPy). The insoluble products were characterized by Fourier transform infrared (FTIR), elemental analysis, scanning electron microscopy (SEM), and four point probe conductivity measurements.

Polypyrrole Dispersions on Poly(methy1 methacrylate)-blok-Poly(acrylic acid) Core-shell Latex

Poly(methyl methacrylate)-block-poly(acrylic acid) (PMMA-b-PAA) core-shell latex has been prepared by hydrolysis of poly(ethyl acrylate) block in poly(methyl methacrylate)-block-poly(ethyl acrylate) which was prepared using cupper mediated ATRP technique. Pyrrole was polymerized oxidatively on the PMMA-b-PAA core-shell latex forming polypyrrole nanoparticles. Presence of the carboxylate groups on the core-shell latex provides stable dispersions Resulting polymers were characterized by spectroscopically, electrochemically and four point-probe conductivity.