Chepuri R. K. Rao

Energy storage and surface protection properties of dianiline co-polymers

Conducting co-polyanilines of alkyl/alkoxy substituted anilines with dianiline, namely poly(OT–DA), poly(OA–DA) and poly(DMA–DA), have been synthesized chemically from o-toluedine(OT), o-anisidine(OA), 2,6-dimethylaniline(DMA) and N-phenyl-p-phenylenediamine (DA). These co-polyanilines were characterized by spectral, thermal and electrochemical techniques. The conductivities of phosphoric acid (PA) doped co-polydianilines are 2.26 × 10−1 S cm−1 for poly(OT–DA), 7.94 × 10−2 S cm−1 for poly(OA–DA) and 9.25 × 10−2 S cm−1 for poly(DMA–DA) at room temperature. The thermal stability of co-polymers is higher in the doped state than in the emeraldine base state. A capacitor has been fabricated using these polymers using stainless steel electrodes. The specific capacitance of the device is 177 F g−1 for poly(OT–DA)–PA, 110 F g−1 for poly(OA–DA)–PA and 121 F g−1 for poly(DMA–DA)–PA at 1 mA cm−2 current density. The anti-corrosion behaviour of co-polydianilines (EB state) coated on mild steel (MS) electrode was investigated by Tafel polarization method and the corrosion rate is found to be 2.07 × 10−6 mm per year for poly(OT–DA)–EB, 1.42 × 10−5 mm per year for poly(OA–DA)–EB and 5.3 × 10−4 mm per year for poly(DMA–DA)–EB.

Biosourced graphitic nanoparticle loaded hyperbranched polyurethane composites – application as multifunctional high-performance coatings

The present work reports the development of a novel nitrogen rich hyperbranched polyurethane-urea nanocomposite using bio-sourced graphitic nanoparticles as an effective filler. Initially, a nitrogen rich hyperbranched polyol is obtained by a two step polycondensation reaction between castor oil derived sebacic acid and triethanolamine. The formation of the hyperbranched polyol was confirmed by using various spectroscopic techniques like FTIR, 1H NMR, 13C NMR and ESI-MS. The resulting hyperbranched polyol with 80% degree of branching was further reacted with carboxyl terminated graphitic nanoparticles in different weight percentages (0, 0.1 and 0.5% with respect to polyol weight) along with a diisocyanate (maintaining an OH : NCO ratio of 1 : 1.2) in order to get polyurethane-urea graphitic nanoparticle hybrid nanocomposites. The results suggest that the incorporation of graphitic nanoparticles improves the thermo-mechanical properties, hydrophobic nature, and bacterial and corrosion resistance of the polyurethane nanocomposite. It is seen that a minuscule incorporation of 0.5% graphitic nanoparticles into the polyurethane matrix improves the storage modulus from 365 to 996 MPa, the glass transition temperature from 67 °C to 95 °C, the water contact angle from 50° to 80° and reduces the corrosion rate from 9.2 × 10−3 to 5.29 × 10−5 mm per year in comparison with neat polyurethane. All these improvements in properties are accredited to the covalent linkage, geometry and uniform distribution of graphitic nanoparticles with the polyurethane matrix. In addition, all the polyurethane hybrids show good stability against various bacterial stains.

Polyurethane-tetraaniline conducting composites: synthesis and their anti-corrosion performance

Purpose – The purpose of this paper is to get the insulating polyurethane (PU) as conductive type polymer by compositing with oligoanilines, namely, tetraaniline (TANi) with an implication of its use as anti-corrosion coating material. Design/methodology/approach – Water dispersion of PU was prepared and used as a host material for TANi for composite formulation. Findings – The composites are very useful as anti-corrosion coating on mild steel as evident from Tafel polarisation studies. Research limitations/implications – The solubility of TANi is limited in other organic solvents; because of this, a high-boiling solvent like N-methyl-2-pyrrolidone (NMP) is used. Practical implications – It can be used as a good anti-corrosion coating on mild steel. Apart from anti-corrosion material, this can be used as conductive-based sensor material and also electrostatic dissipation (ESD) or electromagnetic interference (EMI) shield. Originality/value – The work is original.