Chinnaiah Sivakumar

In situ, UV-Vis spectroelectrochemical studies on the initial stages of copolymerization of aniline with diphenylamine-4-sulphonic acid

Abstract In situ, spectroelectrochemical studies on the copolymerization of aniline (ANI) with diphenylamine-4-sulphonic acid (DPASA) were carried out in 0.5 M H 2 SO 4 for different feed ratios of ANI and DPASA using ITO as the working electrode. Studies on homopolymerization of DPASA and ANI were also done independently in 0.5 M sulphuric acid. UV–Vis absorption spectra were recorded concurrently during the copolymerization and homopolymerizations. The intermediate species for the homopolymerization of DPASA and copolymerization with ANI have been identified by spectroelectrochemical studies. The spectroelectrochemical results revealed the formation of an intermediate at the initial stages of copolymerization through the reaction of the DPASA cation radical and the aniline cation radical to result in a head-to-tail dimer. This N -phenyl- para -phenylene diamine (PPD) type of intermediate was assigned to have a peak at 550 nm in the UV–Vis spectra. The assignment of a peak at 550 nm to the intermediate was further confirmed by deducing derivative cyclic voltabsorptogram (DCVA) at 550 nm. The results from constant potential electropolymerization also supported the formation of an intermediate that absorbs at 550 nm

Studies on processable conducting blend of poly(diphenylamine) and poly(vinylidene fluoride)

Conducting blends of poly(diphenylamine) (PDPA) doped with H2SO4 or p-toluenesulphonic acid (TSA) and poly(vinylidene fluoride) (PVDF) were successfully prepared by using N,N′-dimethyl formamide (DMF) as solvent. Flexible, free-standing and conducting polyblends were obtained by solution casting which are characterized by electrical conductivity measurements, UV–Visible spectroscopy, FTIR spectroscopy, thermogravimetric analysis (TGA), differential scanning colorimetry (DSC), X-ray diffraction analysis, and cyclic voltammetry. The blends showed an increase in conductivity from about 10−9 to 10−5 S cm−1, with a percolation threshold of 5% of PDPA–H2SO4/TSA.

Electroactive conducting blends of poly(o-toluidine) and poly(vinylidene fluoride) and characterisation

Abstract Conducting blends of poly( o -toluidine) (POT) with poly(vinylidene fluoride) (PVDF) were prepared by solution casting method. POT doped with H 2 SO 4 or p -toluene sulphonic acid (PTSA) was used for making the blends. Flexible, free standing conducting polyblends were obtained and characterised by electrical conductivity measurements, UV-Vis, FT-IR spectroscopy, thermogravimetric analysis (TGA), differential scanning colorimetry (DSC) and cyclic voltammetry. The conductivity of the blend was found to increase with POT content in the blend. A low percolation threshold (2%) was noted for the blends. Thermal stability of the blends was found to be better. The changes in the crystalline phase of PVDF were observed through FT-IR spectroscopy and DSC measurements. The blend films were electrochemically stable and showed electrochemical properties similar to POT.

In situ UV-visible spectroelectrochemical evidences for conducting copolymer formation between diphenylamine and m-methoxyaniline.

Electrochemical copolymerization of diphenylamine (DPA) with m-methoxy aniline (MA) was carried out in 4 M H(2)SO(4) by cyclic voltammetry (CV). Cyclic voltammograms (CVs) of the copolymer films were recorded in monomer-free background electrolyte. In situ sepectroelectrochemical studies were carried out on an optically transparent electrode (Indium tin oxide (ITO) coated glass) in 4 M H(2)SO(4) for different feed ratios of the comonomers. Constant potential and potential sweep methods were employed for performing polymerization. UV-visible absorption spectra were collected continuously and concurrently during the copolymerization in both the cases. The results from constant potential electropolymerisation indicated the formation of an intermediate with an absorption peak at 576 nm. Derivative cyclic voltabsorptogram (DCVA) was deduced from the results of cyclic spectrovoltammetry. The DCVA derived at 576 nm confirms the intermediates formed during the electrochemical copolymerization. The compositional changes of the two monomers in the copolymers with changes in feed composition of two monomers as predicted from in situ spectro electrochemical studies are evident from elemental analysis. A plausible copolymerization mechanism is suggested.

In-situ spectroelectrochemical evidences for the copolymerization of o-toluidine with diphenylamine-4-sulphonic acid by UV-visible spectroscopy.

In-situ spectroelectrochemical studies on the copolymerization of o-toluidine (OT) with diphenylamine-4-sulfonic acid (DPASA) were carried out on ITO electrode in 0.5 M H2SO4 for different feed ratios of OT and DPASA. The early stages of copolymerization of OT with DPASA have been identified through spectroelectrochemical techniques. The results revealed the formation of a head-to-tail dimer type of intermediate at the initial stages of copolymerization. This N-phenyl-paraphenylene diamine (PPD) type of intermediate was assigned to have a peak at 550 nm in UV-visible spectra and confirmed via derivative cyclic voltabsorptogram (DCVA). Constant potential electropolymerization results also supported the formation of intermediate with an absorption maximum at 550 nm.

Simultaneous synthesis and doping of poly(1,6-heptadiyne-co-dipropargyl ether) using ionic initiators

Abstract Cyclocopolymerization of 1,6-heptadiyne with dipropargyl ether was carried out under nitrogen atmosphere using KSCN, KBr and KI as initiators in N , N -dimethyl formamide. The course of polymerization was monitored through UV–Vis spectroscopy. The rate of cyclocopolymerization was determined at different polymerization conditions and the relative efficiency of different initiators was evaluated. KSCN was found to be particularly an effective initiator for the copolymerization. The resulting dark brown colour polymer exhibits good solubility in common organic solvents. 1 H-NMR, FTIR and UV–Vis spectra of poly(1,6-heptadiyne- co -dipropargyl ether) revealed that the copolymer possesses cyclic polyene units in the back bone. Doped nature of the polymer was evident from UV–Vis and FTIR spectroscopy. Thermal characteristics, conductivity and electroactivity of the copolymer were also explored.

Growth behavior of poly(o-toluidine-co-p-fluoroaniline) deposition by cyclic voltammetry

Electrochemical copolymerization of o-toluidine (OT) with p-fluoroaniline (FA) was carried out in 1 M HCl by cyclic voltammetry. Polymeric films were deposited by employing different conditions such as cycle number and feed-ratio of comonomers. Electrochemical homopolymerization of OT and FA were also done. A growth equation for copolymer deposition relating the parameters of operation and charge associated for film deposition was obtained. Growth rate constant was determined.

Peroxomonosulphate initiated graft copolymerization of aniline onto poly(propylene) fibre - A kinetic approach

Graft copolymerization of poly(aniline) (PANI) onto poly(propylene) (PP) fibre was carried out in aqueous acidic medium under nitrogen atmosphere by using peroxomonosulphate (PMS) as a lone initiator. The non-conducting fibre was now made into a conducting one through the chemical grafting of PANI units onto the PP fibre backbone. The content of PANI in the backbone was found to vary while varying the [ANI], [PMS] and amount of PP fibre. Various graft parameters were evaluated. The chemical grafting of PANI onto PP fibre was confirmed by conductivity measurements.

Course of poly(4-aminodiphenylamine)/Ag nanocomposite formation through UV-vis spectroscopy.

Kinetics of chemical oxidative polymerization of 4-aminodiphenylamine (4ADPA) was followed in aqueous 1 M p-toluene sulfonic acid (p-TSA) using silver nitrate (AgNO3) as an oxidant by UV-vis spectroscopy. The medium was found to be clear and homogeneous during the course of polymerization. The absorbances corresponding to the intermediate and the polymer were followed for different concentrations of 4ADPA and AgNO3 and at different reaction time. The appearance of a band around 450 nm during the initial stages of polymerization corresponds to the plasmon resonance formed by the reduction of Ag+ ions. Rate of poly(4-aminodiphenylamine)/Ag nanocomposite (RP4ADPA/AgNC) was determined for various reaction conditions. R(P4ADP/AgNC) showed second order power dependence on 4ADPA and first order dependence on AgNO3. The observed order dependences of 4ADPA and AgNO3 on the formation of P4ADPA/AgNC were used to deduce a rate equation for the reaction. Rate constant for the reaction was determined through different approaches. The good agreement between the rate constants obtained through different approaches justifies the selection of rate equation.

Course of conducting poly(1,6-heptadiyne) formation through ultraviolet–visible spectroscopy

Abstract Polymerization of the symmetrical non-conjugated diyne, 1,6-heptadiyne, was carried out in nitrogen atmosphere with different initiators in dimethyl formamide. The course of polymerization was followed through ultraviolet–visible spectroscopy. The rate of polymerization was determined under different conditions and used for comparing the efficiency of the initiators. The poly(1,6-heptadiyne) was isolated and characterized through infrared spectroscopy, conductivity measurements and cyclic voltammetry. The electroactivity of the polymer was revealed.