Proceedings by Francesc Estrany
by X. Ramón Nóvoa, Claudio Cameselle, Francesc Estrany, Juan Feliu, Luísa M D R S Martins, Annick Hubin, Ricardo M Souto, Esther Gil, Griselda Caballero De Snchez, Paramaconi Rodriguez, Carlos Muller, Jaume Puy, and Carmen María Abreu Fernández Libro de abstracts
Papers by Francesc Estrany
European Polymer Journal, 2007
Cell adhesion and proliferation in poly(3,4-ethylenedioxythiophene), an electroactive polythiophe... more Cell adhesion and proliferation in poly(3,4-ethylenedioxythiophene), an electroactive polythiophene derivative generated by anodic polymerization, has been investigated. Results show that epithelial cells Hep-2 present significant activity on the surface of poly(3,4-ethylenedioxythiophene) electrodeposited on stainless steel electrodes, no sign of cytotoxicity being detected for this conducting polymer. Indeed, seeded and cultured cells bound better to poly(3,4-ethylenedioxythiophene) than to uncoated stainless steel,
Polymer, 2008
A comparative study about cross-linking in electrogenerated polypyrrole and poly(N-methylpyrrole)... more A comparative study about cross-linking in electrogenerated polypyrrole and poly(N-methylpyrrole) is presented. Experimental studies on polymer films prepared under a constant potential of 1.4 V but considering different polymerization times as well as quantum mechanical calculations on model oligomers indicated that cross-linking is very low in polypyrrole, while cross-links are frequently formed by poly(N-methylpyrrole) chains. These behaviors have been attributed to the architecture of the molecular chains, which is completely different for the two systems under study. Thus, polypyrrole forms linear chains with some irregularities in the inter-ring linkages, while branched molecules with many irregularities are the most stable for poly(N-methylpyrrole). These remarkable differences are fundamentally due to the steric repulsions induced by the methyl groups of poly(N-methylpyrrole).
Thin Solid Films, 2010
Multilayered nanometric films formed by alternated layers of conducting poly(3,4-ethylenedioxythi... more Multilayered nanometric films formed by alternated layers of conducting poly(3,4-ethylenedioxythiophene) and poly(N-methylpyrrole) doped with perchlorate anions (ml-PEDOT/PNMPy) have been prepared using a layerby-layer electrodeposition technique combined with a very small polymerization time. The mechanisms of formation and growth of the resulting multilayered systems have been investigated using Atomic Force Microscopy (AFM), and compared with those obtained for the corresponding homopolymers, which were prepared using identical experimental conditions. Furthermore, the local conductivity, electroactivity and electrostability have been also examined. Analyses of the morphology, topography and roughness of the surfaces indicate that the formation and growth of the multilayered films strongly depend on the number of layers as well as on the chemical nature of the conducting polymer. Interestingly, AFM reflects that the formation and growth of the ml-PEDOT/PNMPy films are significantly different from those of PEDOT and PNMPy homopolymers. The electrical and electrochemical properties of the systems under study are fully consistent with the proposed mechanisms. Results evidenced that multilayered systems formed by two conducting polymers are more advantageous from a technological point of view than the corresponding copolymers.
The Journal of Physical Chemistry B, 2010
A new substituted polythiophene derivative bearing malonic acid, poly(2-thiophen-3-yl-malonic aci... more A new substituted polythiophene derivative bearing malonic acid, poly(2-thiophen-3-yl-malonic acid), has been prepared and characterized using a strategy that combines both experimental and theoretical methodologies. The chemical structure of this material has been investigated using FTIR and (1)H NMR, and its molecular conformation has been determined using quantum mechanical calculations. Interestingly, the arrangement of the inter-ring dihedral angles was found to depend on the ionization degree of the material, that is, on the pH, which has been found completely soluble in aqueous base solution. Thus, the preferred anti-gauche conformation changes to syn-gauche when the negatively charged carboxylate groups transforms into neutral carboxylic acid. UV-vis experiments and quantum mechanical calculations on model systems with a head-to-tail regiochemistry showed that the lowest pi-pi* transition energy is 2.25 and 2.39 eV for the negatively charged and the neutral polymer, respectively. These values are slightly larger than those previously reported for other polythiophenes with bulky polar side groups. The polymer presents a good thermal stability with a decomposition temperature above 215 degrees C and an electrical conductivity of 10(-5) S/cm, which is characteristic of semiconductor materials. Scanning electron microscopy micrographs showed that, after doping, the surface of this material displays regular distribution pores with irregular sizes. This surface suggests that poly(2-thiophen-3-yl-malonic acid) is a candidate for potential applications such as selective membranes for electrodialysis, wastewater treatment, or ion-selective membranes for biomedical uses.
Progress in Organic Coatings, 2007
Within coating technology, there is increasing interest in the development of efficient anticorro... more Within coating technology, there is increasing interest in the development of efficient anticorrosive additives able to replace the conventional inorganic anticorrosive pigments usually added to paints, which may have detrimental effects on both environment and health. A number of recent studies have evidenced that the modification of a paint formulation by the addition of a low concentration of conducting polymer (0.2-0.3%, w/w) increases significantly the protective properties of the coating. Here we focus on the principles of anticorrosive additives based on conducting polymers for marine paints. The article reviews the most important findings achieved in recent studies. The relevant factors that are determinant for the anticorrosive protection imparted by conducting polymers, as the doping level, the miscibility with paint, the electrochemical stability, etc., are discussed in detail.
Polymer International, 2007
The structural, electric and electronic properties of copolymers derived from mixtures of Nmethyl... more The structural, electric and electronic properties of copolymers derived from mixtures of Nmethylpyrrole and 3,4-ethylenedioxythiophene (EDOT) with various concentration ratios have been investigated and, additionally, compared with those of the corresponding homopolymers. The electropolymerization kinetics of all the generated copolymers and the homopolymers was examined in terms of current productivity using chronoamperometry. The chemical structure of the linkages between adjacent monomers and the microstructure of the chains were investigated using Fourier transform infrared spectroscopy and quantum mechanical calculations, respectively. The results indicate that the linkages between monomeric units formed during the anodic copolymerization are of the α -α type, while the microstructure of the copolymers depends on the EDOT content. Theoretical calculations were also used to examine the electronic properties of the systems under study, while the conductivity and the electrical stability were studied using the sheet-resistance method. Interestingly, the electric properties are consistent with the random and block microstructures predicted for the copolymers with low and high EDOT content, respectively.
Polymer, 2009
The interaction between poly(3,4-ethylenedioxythiophene), a conducting polymer with excellent ele... more The interaction between poly(3,4-ethylenedioxythiophene), a conducting polymer with excellent electrical and electrochemical properties, and plasmid DNA has been investigated using electrophoresis, UVvisible and CD spectroscopy, and quantum mechanical calculations. Analyses of mixtures with different DNA:polymer mass ratios indicate that, in all cases, interactions form immediately and induce structural alterations in DNA. Furthermore, the existence of interactions between poly(3,4-ethylenedioxythiophene) and specific nucleotides sequences has been evidenced by adding restriction enzymes to the mixtures. In contrast, interactions between DNA and poly(3-methylthiophene), a similar polyheterocyclic conducting polymer but without hydrogen bonding acceptors, are weak or do not exist. These results suggest that, in addition to non-specific electrostatic interactions between the charged phosphate groups of DNA and the positively charged fragments of the conducing polymers, specific hydrogen bonding interactions play a crucial role. The ability of 3,4-ethylenedioxythiophene units to form hydrogen bonds with the methylated analogues of DNA bases has been examined in different environments using MP2/6-31G(d) and MP2/6-311þþG(d,p) calculations. Results indicate that, in environments with low polarity, the formed interactions are significantly stronger than those reached by unsubstituted thiophene and similar to those established by pyrrole. However, in polar environments (aqueous solution) 3,4-ethylenedioxythiophene provides stronger interactions with nucleic acids than both thiophene and pyrrole. These theoretical results are fully consistent with experimental observations.
Polymer, 2008
This work presents a combined theoretical and experimental study of poly(3-thiophene-3-yl acrylic... more This work presents a combined theoretical and experimental study of poly(3-thiophene-3-yl acrylic acid), a new polythiophene derivative soluble in polar solvents. Quantum chemical calculations on small oligomers were performed to propose a structural model for this polymer. Specifically, the minimum energy conformations and the rotational profiles of the different isomeric derivatives constructed for a model system formed by two monomeric units were calculated. The resulting model, which shows head-to-tail polymer linkages and the acrylic acid side group arranged in trans-conformation, were used to predict the pep* lowest transition energy of an infinite polymer chain. On the other hand, the polymer was prepared by chemical oxidative coupling using anhydrous ferric chloride and subsequent alkaline hydrolysis. The synthetized material, which is soluble in aqueous base and acetone solutions, was characterized by FTIR, 1 H NMR and UVevis experiments. Both the structural information and electronic properties derived from such experiments are fully consistent with the theoretical model obtained using quantum mechanical calculations.
Polymer, 2007
Quantum chemical calculations on small idealized systems of poly(3-thiophen-3-yl-acrylic acid met... more Quantum chemical calculations on small idealized systems of poly(3-thiophen-3-yl-acrylic acid methyl ester), a new polythiophene derivative soluble in polar solvents, have been performed to propose a model for this polymer. The model, which was derived from calculations at the HF/ 6-31G(d) and B3PW91/6-31þG(d,p) levels is defined by both the head-to-tail polymer linkages and the conformation of the acrylic acid methyl ester side groups. The pep* lowest transition energy predicted for the polymer is in excellent agreement with the experimental values, which were determined in this work using UVevisible experiments. Finally, we investigated the variation of the electronic properties produced by small chemical modifications in the side group of poly(3-thiophen-3-yl-acrylic acid methyl ester), such changes being designed to enhance the solubility of the polymer in water.
Materials and Corrosion, 2007
Multilayered systems containing 3 or 5 layers of poly (3,4ethylenedioxythiophene) and poly(N-meth... more Multilayered systems containing 3 or 5 layers of poly (3,4ethylenedioxythiophene) and poly(N-methylpyrrole) have been prepared using a layer-by-layer electrodeposition technique. These multilayered systems have been found to present very high electroactivities suggesting that their performance as anti-corrosive additive of conventional organic coatings (paints) could be even better than that of single-component conducting polymers. The perform-ance of the prepared multilayered systems as anti-corrosive additives of epoxy paints has been checked. For this purpose, accelerated corrosion tests were performed using an aggressive solution medium. Analysis of the corroded area indicates that the addition of a low concentration (0.2% w/w) of these multilayered systems to the paint formulation enhances significantly the corrosion protection imparted by the coating.
Macromolecular Materials and Engineering, 2007
Macromolecular Materials and Engineering, 2012
Macromolecular Materials and Engineering, 2012
ABSTRACT Lysozyme, an enzyme with bactericidal activity over Gram-positive bacteria cells, is inc... more ABSTRACT Lysozyme, an enzyme with bactericidal activity over Gram-positive bacteria cells, is incorporated into PEDOT to prepare films with high biological and electrochemical activity. Two different strategies are used: (1) PEDOT films are coated with a layer of enzyme, which was adsorbed on the surface; and (2) the lysozyme is added to the polymerization medium used for the preparation of the conducting polymer. The enzyme adsorbed at the surface of the polymer produces a biphasic system that retains the electrochemical properties of the conducting polymer but is not able to protect against bacterial growth. In contrast, the addition of lysozyme to the polymerization medium results in a homogeneous composite with high bactericidal and electrochemical activities.
Macromolecular Chemistry and Physics, 2010
Macromolecular Chemistry and Physics, 2010
Macromolecular Bioscience, 2008
This work reports a comprehensive study about cell adhesion and proliferation on the surface of d... more This work reports a comprehensive study about cell adhesion and proliferation on the surface of different electroactive substrates formed by p-conjugated polymers. Biological assays were performed considering four different cellular lines: two epithelial and two fibroblasts. On the other hand, the electroactivity of the three conducting systems was determined in physiological conditions. Results indicate that the three substrates behave as a cellular matrix, even though compatibility with cells is larger for PPy and the 3-layered system. Furthermore, the three polymeric systems are electro-compatible with the cellular monolayers.
Journal of Polymer Research, 2008
Copolymers derived from mixtures of pyrrole and N-(hydroxypropyl)pyrrole have been prepared elect... more Copolymers derived from mixtures of pyrrole and N-(hydroxypropyl)pyrrole have been prepared electrochemically using various concentration ratios. Copolymers were generated on stainless electrodes by chronoamperometry and cyclic voltammetry in a LiClO4 acetonitrile solution. Relevant physical (density and doping level) and electrochemical (electroactivity and electrostability) properties of the copolymers have been examined and compared with those of the two corresponding homopolymers, which
Journal of Polymer Research, 2006
We report here the one-step electrochemical synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT)... more We report here the one-step electrochemical synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) in an aqueous dispersion of reduced graphene oxide (rGO). The electrochemical polymerization is carried out at 1.05 V in aqueous media in the presence of 10 À2 M 3,4-ethylenedioxythiophene and 1 g L À1 rGO. Unlike composites of PEDOT and graphene oxide or poly(styrene sulfonate) which have rather smooth and non-porous surface morphologies, the scanning electron microscopy images reveal that the PEDOT composite films obtained in this work have uniformly porous and open surface morphology. X-ray photoelectron spectroscopy (XPS) showed that rGO had initially a low concentration of oxygencontaining surface groups (C : O ratio ¼ 6.5), but both FTIR spectroscopy and XPS showed that the electropolymerization resulted in the formation of OH groups in the composite film. Characterization with cyclic voltammetry and electrochemical impedance spectroscopy demonstrates that the composite films behave almost like ideal capacitors having an areal capacitance of 12.2 mF cm À2 . The composite films had a very good potential cycling stability in 0.1 M KCl with only 12.4% degradation of the capacitance in a three-electrode cell after 3000 cycles between À0.5 and 0.5 V. The degradation was higher (32.8%) in the broader potential range of À0.8 and 0.7 V.
Uploads
Proceedings by Francesc Estrany
Papers by Francesc Estrany