Extending the utility of conducting polymers through chemisorption of nucleophiles

The investigation of poly(3,4-ethylenedioxythiophene) (PEDOT) exposed to several example amines has shown that they bind to the conducting polymer through a nucleophilic attack on the positively charged carbon atoms. The PEDOT films were polymerized using the vacuum vapor phase polymerization (VPP) technique, and their electrical and optical properties subsequently modified by adsorbing aniline, ammonia or urea. Analysis of the surface chemistry shows that the reversibility of the binding depends on the nature of the amine, although a portion is chemisorbed to the PEDOT. This mechanism allows the polymer surface to be decorated with biomolecules or nanoparticles, as demonstrated by attachment of poly(allylamine) coated silica nanoparticles to the PEDOT. This understanding provides the opportunity to control PEDOT properties, and opens the pathway to extend the utility of these electroactive, optoactive, and bioactive materials.Pejman Hojati-Talemi, Drew Evans, and Manrico Fabrett

Effect of different microwave-based treatments on multi-walled carbon nanotubes

Three new methods for the functionalization of multi-walled carbon nanotubes (MWCNTs) are reported using microwave (MW) energy and water as a mild chemical agent. In the first method we reported the effect of MW irradiation on a dispersion of MWCNTs in deionized water, in the second method we studied the exposing of MWCNT to microwave irradiation in the presence of steam, and in the third method we used microwave oven-generated plasma for the functionalization of MWCNTs. We also performed thermal oxidation and acid treatment as two conventional methods for oxidative functionalization of carbon nanotubes, to compare their effect with our results. Transmission electron microscopy (TEM) and Raman spectroscopy results showed that although these microwave methods introduced some defects to the carbon nanotubes, the damage was less severe than conventional treatments. X-ray photoelectron spectroscopy (XPS) measurements confirmed that the functionalization of carbon nanotubes by these methods favored hydroxyl groups, which are useful when further functionalization is required.Pejman Hojati-Talemi, Raoul Cervini, George P. Simo

Highly efficient low voltage electron emission from directly spinnable carbon nanotube webs

Abstract not availablePejman Hojati-Talemi, Stephen C. Hawkins, Chi P. Huynh, George P. Simo

Understanding parameters affecting field emission properties of directly spinnable carbon nanotube webs

Abstract not availablePejman Hojati-Talemi, Stephen Hawkins, Chi Huynh, George P. Simo

Fusion of carbon nanotubes for fabrication of field emission cathodes

Consolidated carbonaceous samples prepared by spark plasma sintering of multi-walled carbon nanotubes are analyzed, and the effect of the heating regime on their morphology, density, thermal stability, electron field emission and adhesive behavior studied. The trend in the field emission properties of these samples is explained by the changes in the mobility of the nanotube tips. The effect of such changes in the number of free nanotube tips is also deduced from micro-adhesion data, obtained from pull-off tests using atomic force microscopy

Using oxygen plasma treatment to improve the performance of electrodes for capacitive water deionization

Abstract not availablePejman Hojati-Talemi, Linda Zou, Manrico Fabretto, Robert D. Shor

Enhancing the morphology and electrochromic stability of polypyrrole via PEG-PPG-PEG templating in vapour phase polymerisation

Abstract not availableRobert Brooke, Drew Evans, Pejman Hojati-Talemi, Peter Murphy, Manrico Fabrett

Ultrathin polymer films for transparent electrode applications prepared by controlled nucleation

Publication Date (Web): October 23, 2013The vacuum vapor phase polymerization (VPP) technique is capable of producing conducting polymer films with conductivities up to 3400 S cm(-1). However, the method is not able to produce robust nano-thin films as required for transparent conducting electrode (TCE) applications. We show that with the addition of aprotic solvents or chelating agents to the oxidant mixture, it is possible to control the polymerization rate, and nucleation, in the VPP process. This provides the opportunity of altering the grain size and depositing conducting polymer films with a thickness of 16 to 200 nm with resulting optical transmission within the range 50-98% that are robust enough to endure the post polymerization processing steps. The figure of merit (FoM), which is used to quantify a film's suitability for TCE applications, results in values from 12 to 25. This result indicates that the nano-films outperform most of the previously reported graphene films and approaches the accepted industry standard for TCE applications.Pejman Hojati-Talemi, Curdin Bächler, Manrico Fabretto, Peter Murphy, and Drew Evan

Synthesis and structural characterization of new lead(II) discrete and infinite cage-like framework: a precursor to produce pure phase nano-sized lead(II) oxide

A novel Pb(II) complex, {[Pb2(tpmba)2(NO3)4]·MeOH} n (1), was obtained by the reaction of a tripodal ligand, N,N′,N″-tris(pyrid-3-ylmethyl)-1,3,5-benzenetricarboxamide (tpmba), with Pb(NO3)2. The structure of complex was determined by X-ray crystallography. The results of structural analysis of the complex reveal that 1 is a M2L2 cage-like with a methanol molecule beside the cage. An entirely different structure and topology between 1 and similar complexes indicate that the nature of organic ligands affects the structure of assemblies. The results indicate that the framework of this complex is predominated by the nature of the organic ligand, anions, solvent and geometric need of the metal ions. It was found that the coordination number of PbII ions is eight, (PbN3O5) has a stereo-chemically active electron lone pair and the coordination sphere is hemi-directed. PbO nanoparticles are obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. Scanning electron microscopy shows that the size of the PbO particles is ~30 nm.Gholam Hossein Shahverdizadeh, Fateme Hakimi, Babak Mirtamizdoust, Aliakbar Soudi, Pejman Hojati-Talem

A theoretical practice on grazing-exit energy dispersive X-ray spectroscopy as a surface analysis strategy to investigate BiVO4 nano-films

Abstract not availableHosein Golmojdeh, Mohammad Ali Zanjanchi, Shabnam Sohrabnejad, Jamal Mazloom and Pejman Hojati-Talem