D. G. Hundiwale

Influence of inorganic and organic supporting electrolytes on the electrochemical synthesis of polyaniline, poly(o-toluidine) and their copolymer thin films

The influence of inorganic and organic supporting electrolytes on electrochemical, optical and conducting properties of polyaniline (PA), poly(o-toluidine) (POT) and poly(aniline-co-o-toluidine) (PA–POT) thin films have been investigated. The films were synthesized electrochemically individually and then combinedly as copolymer under cyclic voltammetric conditions in aqueous solutions of inorganic acids viz. H2SO4, HCl, HNO3, H3PO4 and HClO4 and organic acids viz. benzoic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid and adipic acid at room temperature. The electrosynthesized films were characterized by cyclic voltammetry, UV–visible spectroscopy and conductivity measurement using four-probe technique. It was observed that the current densities are strongly influenced by the size and the nature of the anion present in the electrolyte. The optical absorption spectra indicate the formation of the conducting emeraldine salt (ES) phase irrespective of the inorganic electrolytes, whereas it shows dependence on organic acid supporting electrolytes. Among organic acids, the formation of thin films by cyclic voltammetry and the conducting ES phase was observed only in the case of oxalic acid. It was also found that the conductivity of thin films is greatly affected by the nature and size of the anion present in the electrolyte.

Synthesis of core―shell polystyrene nanoparticles by surfactant free emulsion polymerization using macro-RAFT agent

Novel approach for the synthesis of core-shell polystyrene nanoparticles by living hydrophilic polymer consisting of thiocarbonyl thio end group is reported. The surfactant free emulsion polymerization of styrene in the presence of macro-RAFT (reversible addition fragmentation chain transfer) agent is carried out to synthesize stable latex particles with smaller particle size. A macro-RAFT agent is prepared by homopolymerization of sodium styrene sulfonate (NaSS) in aqueous phase by using dithioester as chain transfer agent. This synthesized polystyrene sulfonate-sodium (PSS-Na) based macro-RAFT agent, which is essentially water soluble macromolecular chain transfer agent used for the surfactant-free batch emulsion polymerization of styrene. Transmission electron microscopy (TEM) study of the synthesized colloids shows the narrow particle size distribution with core-shell morphology.

Effect of inorganic dopants (in presence of electrolyte) on the conductivity of polyaniline, poly(o-toluidine) and their copolymer thin films

Abstract An attempt has been made to prepare polyaniline (PA), poly(o-toluidine) (POT) and copolymer (PA-POT) thin films doped by several inorganic salts (sulphates and chlorides) with varying size of cation using aqueous solution of H2SO4 as electrolyte. Effect of dopant in presence of electrolyte is rarely studied in the field of conducting polymers. Various inorganic salts as dopants, viz. K2SO4, Na2SO4, Li2SO4, MgSO4, KCl, NaCl, LiCl and MgCl2 are used at room temperature. The films were electropolymerized in solution containing 0.1 M monomer, 1 M H2SO4 as electrolyte and 1 M inorganic salt by applying sequential linear potential scan rate 50 mV/s between −0.2 and 1.0 V versus Ag/AgCl electrode. The electrosynthesized films were characterized by cyclic voltammetry, UV–visible spectroscopy and conductivity measurements using four-probe technique. It was observed that the UV–visible peaks are appearing at about 800–810 nm with a shoulder at 410–420 nm for emeraldine salt (ES) phase of PA, POT and PA-POT without any doping salt. In the presence of salts, a shift for these absorption spectra is observed to lower wavelength in 760–800 nm, however, a shift of shoulder is to higher wavelength in 435–445 nm. In the overall study, an increase in conductivity is observed for all above-mentioned dopants, and among these, K2SO4 is found to be the best in sulphate category and KCl in chloride category.

Studies on electrochemical, optical and electrical conductivity characteristics of copolymer of polyaniline-co-poly(o-toluidine) using various organic salts

An attempt has been made to prepare polyaniline (PA), poly(o-toluidine) (POT) and their copolymer polyaniline-co-poly(otoluidine) (PA–POT) thin films doped by several organic salts with varying size of cation, using aqueous solution of H2SO4 as electrolyte. Effect of dopant in the presence of electrolyte is rarely studied in the field of conducting polymers. Various organic salts as dopants, viz. potassium acetate, sodium acetate and magnesium acetate were used at room temperature. The films were electropolymerized in solution containing 0.1 M monomer(s), 1 M H2SO4 as electrolyte and 1 M organic salt by applying sequential linear potential scan rate 50 mV/s between 0.2 and 1.0 V versus Ag/AgCl electrode. The electro-synthesized films were characterized by cyclic voltammetry, UV–Visible spectroscopy and conductivity measurements. The UV–Visible spectra were obtained ex situ in dimethyl sulfoxide (DMSO) and peaks are observed to appear at about 800–810 nm with a shoulder at 410–420 nm are for emeraldine salt (ES) phase of PA, POT, PA–POT without any doping salt. In the presence of salts, a shift for these absorptions was observed to lower wavelength (758–786 nm), however, a shift of shoulder to higher wavelength (413–425 nm). In overall study, an increase in conductivity was observed for all aforesaid dopants and among these, potassium acetate was found to be the best. D 2003 Elsevier Science B.V. All rights reserved.

Controlled Release Study of Phenol Formaldehyde Microcapsules Containing Neem Oil as an Insecticide

Many of the biological pesticides are supposed to be more effective than synthetic ones in controlling pests. In this communication, we report a successful encapsulation of neem oil, one of the most effective biological insecticides, in phenol formaldehyde microcapsules. This was achieved by adopting an in-situ polymerization process in oil-in-water emulsion. The synthesis consists of two parts, namely emulsification of the oil and wall formation. The synthesized microcapsules were characterized by FTIR, SEM, TGA, and particle size analyzer. The controlled release was monitored by measuring optical observation in the UV range.

Conducting polymers: an emerging field of biosensors

Conducting polymers have attracted much interest in the development of biosensors. Electrically conducting polymers are known to possess numerous features, which allow them to act as excellent materials for immobilization of biomolecules and rapid electron transfer for the fabrication of efficient biosensors. The present review describes the salient features of conducting polymers as biosensors, their construction, working, importance and applications.

Synthesis and characterisation of polyurethane coatings based on trimer of isophorone diisocyanate (IPDI) and monoglycerides of oils

SummariesMonoglycerides (MGs) of four oils (castor, linseed, soybean and sesame) were prepared. They were reacted with a trimer in definite proportions to prepare polyurethane (PU) coatings. These coatings were applied in the form of thin films on tin plates and analysed for various coating properties such as gloss, scratch resistance, flexibility properties and physicochemical tests. A highly cross-linked product was obtained due to the higher functionality associated with MGs compared with their molecular weight. The trimer also imparted cross-linking due to its trifunctionality, and a hard yet flexible, tough, glossy polyurethane coating was obtained.RésuméDes monoglycérides (MGs) de quatre huiles (ricin, lin, soya et sésame) ont été préparés. On les a fait réagir, dans des proportions définies, avec une trimère afin de produire des revêtements polyuréthaniques (PU). Ces revêtements ont été appliqués, sous la forme de minces films, à des plaques d’étain, et ont été analysés afin de constater des propriétés de revêtement variées, telles que le brillant, la résistance aux éraflures, les propriétés de flexibilité et [leur performance au cours] des essais physicochimiques. On a obtenu un produit qui était très réticulé grâce à la fonctionnalité plus élevée associée aux MGs par rapport à leur poids molaire. La trimère, aussi, a donné de la réticulation, grâce à sa trifontionnalité, et l’on a obtenu un revêtement polyuréthanique qui était robuste et brillant mais aussi flexible.ZusammenfassungDie Monoglyzeride (MGs) von vier Ölen (Rizinus, Leinsamen, Soja und Sesam) wurden hergestellt und mit einem Trimer in bestimmten Proportionen reagiert, um Polyurthanlacke herzustellen. Diese Lacke wurden in dünnen Schichten auf Zinkplatten aufgebracht und nach verschiedenen Eigenschaften wie Glanz, Kratzfestigkeit, Flexibilität und ihren physiochemischen Eigenschaften bewertet. Dank der grösseren Funktionalität im Verhältnis zu ihrem Molekulargewicht erzielten wir mit den MGs ein stark kreuzvernetztes Produkt. Die dreifache Funktionalitat der Trimere trug auch zu der Kreuzvernetzung bei, und der erhaltene Polyurethanlack war sowohl hart als auch flexibel, widerstandsfähig und glänzend.

Studies on Influence of Inorganic Dopants in Presence of Electrolyte on the Conductivity of Polyaniline, Poly(o-Anisidine), and Their Copolymer Thin Films

An attempt was made to prepare polyaniline (PA), poly(o-anisidine) (POA), and copolymer polyaniline–poly(o-anisidine) (PA–POA) thin films dopped by several inorganic saltas (sulfates and chlorides) with varying sizes of cations using an aqueous solution of H2SO4 as an electrolyte. Various inorganic salts as dopants, viz., K2SO4, Na2SO4, Li2SO4, MgSO4, KCl, NaCl, LiCl, and MgCl2, were used at room temperature. The films were electropolymerized in solution containing 0.1-M monomer(s), 1-M H2SO4 as electrolyte, and 1-M inorganic salt by applying sequential linear potential scan rate 50 mV/s between −0.2 to 1.0 V vs Ag/AgCl electrode. The electrosynthesized films were characterized by cyclic voltammetry, UV–visible spectroscopy, and conductivity measurements, using a four-probe technique. It was observed that the UV–visible peaks usually appearing at about 810 to 826 nm with a shoulder at 416 to 426 nm, showed a shift in presence of doping salt for the emeraldine salt (ES) phase of PA, POA, PA–POA. In the overall study, a significant increase in conductivity is observed for all dopants mentioned above, and among them K2SO4, is found to be the best in sulfate category and KCl in chloride category.

Effect of Nano–Magnesium Hydroxide on Mechanical and Flame-Retarding Properties of SBR and PBR: A Comparative Study

Magnesium hydroxide [Mg(OH)2] is one of the potential inorganic fillers. In this work, nanoparticles (37±5 nm) of the magnesium hydroxide were prepared using matrix-mediated growth and control technique, and their size was confirmed by X-ray diffraction technique. Nano-Mg(OH)2-SBR and nano-Mg(OH)2-PBR composites with 2–10% (w/w) filler loading were prepared by compounding on laboratory-scale two-roll mill and a compression molding machine. These composites were tested for tensile and physical properties, and the properties were compared with the composites of commercial Mg(OH)2. The incorporation of nanofiller improved the properties of nanocomposites.

Electrochemical synthesis of poly(o-anisidine), poly(o-toludine) and their copolymers in organic sulphonic acid

The effect of organic sulphonic acids on electrochemical, optical and conductivity properties of poly( o -anisidine) (POA), poly( o -toluidine) (POT) and poly(o-anisidine-co-o-toluidine) (POA-co-POT) thin films has been investigated. The films were synthesized electrochemically, individual as homopolymers and then combined as (binary copolymer) under cyclic voltammetric conditions in an aqueous solution of sulphuric acid, p-toluene sulphonic acid, sulphamic acid and sulphosalicylic acid at room temperature. The films were electropolymerized in solution containing 0.1 M monomers and respective electrolyte (1 M sulphuric acid or organic sulphonic acid) by applying sequential linear potential scan rate of 50 mV/s between-0.2 and 1.0 V versus Ag/AgCl electrode. The electrosynthesized films were characterized by cyclic voltammetry, UV-Vis spectroscopy and conductivity measurement. It is observed that the UV-Vis peaks for sulphuric acid, p-toluene sulphonic acid, sulphamic acid and sulphosalicylic acid appear in the region of the conducting emeraldine salt (ES) phase. Overall, the polymers prepared using all these three organic sulphonic acids have higher conductivity than sulphuric acid; however, the higher conductivity is observed for p-toluene sulphonic acid as electrolyte in comparison with sulphamic acid and sulphosalicylic acid. The formation of copolymer (POA-co-POT) has been supported and confirmed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) studies. A possible scheme of reaction mechanism for homo- and copolymer has been suggested.