Abstract  We have prepared and characterized polyaniline in the form of thin free-standing films and films formed by spin coating. The films are formed from solution with chemically prepared base polyaniline (emeraldine) which is dissolved in N-methyl-2-pyrrolidone. The films, as prepared and doped with HCl, have conductivities in the range 60-70 S/cm. Optical reflection spectra reveal metallic-like films. Furthermore, we have been able to align the polyaniline (PANi) chains using uniaxial stress. Elongation ratios of up to 650% have been achieved so far. When doped with HCl these films yield conductivities of up to 350 S/cm and anisotropy sigma-parallel to/sigma-perpendicular to of up to 24. Initial polarized reflection spectra reveal optical anisotropy.

Abstract  Modification of polymeric membrane materials by incorporation of hydrophilicity results in membranes with low fouling behavior and high flux. Hence, polyetherimide (PEI) was functionalized by sulfonation and ultrafiltration membranes were prepared based on cellulose acetate (CA) and sulfonated poly (ether imide) (SPEI) in various blend compositions in N-methyl-2-pyrrolidone (NMP) as solvent by phase inversion technique. Prepared membranes were subjected to ultrafiltration characterizations such as compaction, pure water flux, water content, and membrane hydraulic resistance. All CA/SPEI blend membranes had substantially higher pure water flux, water content, and reduced hydraulic resistance compared to the pure CA membrane. Further, all of these above properties varied systematically with variation of SPEI content. Studies were carried out to find the rejection and permeate flux of macromolecular proteins such as trypsin, pepsin, egg albumin (EA), and bovine serum albumin (BSA) and toxic heavy metal ions such as Cu(2+), Ni(2+), Zn(2+), and Cd(2+) using polyethyleneimine as the chelating agent. On increasing the concentration of SPEI, the rejection of proteins and metal ions decreases whereas the permeate flux has an increasing trend. The molecular weight cut-offs (MWCO) of the blend membranes were determined using protein separation studies found to vary from 20 to 69 kDa, depending on the various polymer compositions. In general it was found that CA/SPEI blend ultrafiltration membranes demonstrated better performance compared to the membranes prepared from pure cellulose acetate.

Abstract  Liquid-phase exfoliation is one of the most promising routes for large-scale production of multilayer graphene dispersions. These dispersions, which may be used in coatings, composites, or paints, are believed to contain disorder-free graphene multilayers. Here, we address the nature of defects in such samples obtained by liquid-phase exfoliation of graphite powder in N-methyl-2-pyrrolidone. Our Raman spectroscopy data challenge the assumption that these multilayers are free of bulk defects, revealing that defect localization strongly depends on the sonication time. For short ultrasound times, defects are located mainly at the layer edges but they turn out to build up in the bulk for ultrasonic times above 2 h. This knowledge may help to devise better strategies to achieve high-quality graphene dispersions.

Abstract  The effectiveness of Koch-Sulzer BX structured packing and random protruded packing are compared for an extractive distillation operation which exhibits high liquid to vapor ratios. The extractive distillation operation studied separated an 88/12wt% toluene/heptane mixture with N-methyl pyrrolidone (NMP) as the solvent in a 0.15 m diameter column with about 5.5 m of packing. The effect of pressure drop and HETP on gas capacity factor, liquid loading and liquid-to-vapor ratio are examined.

Abstract  The examination of the structural characteristics of the substances extracted from four coal samples, using N-methyl-2-pyrrolidinone, was carried out by pyrolysis-field ionization mass spectrometry (Py-FIMS). The extracts are complex mixtures of relatively easily distillable components and of larger entities, supposed to be "oligomeric" parts of the coal structure, which are pyrolyzed above 400-degrees-C with the production of hydroxylated derivatives. Polycondensed structures predominate (4 to 7-8 nuclei) in a wide range of m/z values, mainly 250-350. This work can serve as a basis for further studies on the carbonization process of coals and the role of "the extractible phase" in the first stages of the plastic state and the process of coal softening.

Abstract  This study sought to develop an injectable formulation for long-term ocular delivery of fluocinolone acetonide (FA) by dissolving the anti-inflammatory drug and the biodegradable polymer poly(propylene fumarate) (PPF) in the biocompatible, water-miscible, organic solvent N-methyl-2-pyrrolidone (NMP). Upon injection of the solution into an aqueous environment, a FA-loaded PPF matrix is precipitated in situ through the diffusion/extraction of NMP into surrounding aqueous fluids. Fabrication of the matrices and in vitro release studies were performed in phosphate buffered saline at 37 degrees C. Drug loadings up to 5% were achieved. High performance liquid chromatography was employed to determine the released amount of FA. The effects of drug loading, PPF content of the injectable formulation, and additional photo-crosslinking of the matrix surface were investigated. Overall, FA release was sustained in vitro over up to 400 days. After an initial burst release of 22 to 68% of initial FA loading, controlled drug release driven by diffusion and bulk erosion was observed. Drug release rates in a therapeutic range were demonstrated. Release kinetics were found to be dependent on drug loading, formulation PPF content, and extent of surface crosslinking. The results suggest that injectable, in situ formed PPF matrices are promising candidates for the formulation of long-term, controlled delivery devices for intraocular drug delivery.

Abstract  UNLABELLED: Here, we fabricated a highly conductive poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (

PEDOT: PSS) nanofilm via vacuum filtration with enhanced thermoelectric power factor by doping of liquid exfoliated graphene (GE) and hydrazine treatment. The effect of GE exfoliated in dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) on the electrical conductivity and thermopower of

PEDOT: PSS was investigated. Although electrical conductivity decreased with increasing GE, thermoelectric power factors of

PEDOT: PSS nanofilms were improved with 3 wt % GE in DMF (38.6 μW m(-1) K(-2)) and in NMP (28.0 μW m(-1) K(-2)) compared to pure

PEDOT: PSS (11.5 μW m(-1) K(-2)). The mechanism of improvement was proposed to be the removal of PSS and the good interaction between PEDOT and GE. With hydrazine treatment, 3 wt % GE-doped

PEDOT: PSS nanofilm (PG3) showed a further enhanced power factor of 53.3 μW m(-1) K(-2) (∼5 times higher than that of pristine

PEDOT: PSS nanofilm). The effects of hydrazine containing concentration, treatment time, and temperature on the electrical conductivity and Seebeck coefficient of PG3 were investigated systematically. An estimated thermoelectric figure of merit (ZT) is 0.05 with the optimized power factor at room temperature.

Abstract  At room temperature, silver nano-sized particles were one-step prepared by a novel facile method of the reduction of silver nitrate with o-Phenylenediamine (o-PD) in a mixed solution of water and N-Methyl-2-pyrrolidone(NMPD). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to characterize as-prepared silver nanoparticles. The SEM images show that silver nano-particles are well spherical and possessed of uniform particle size, and the average particle size is about 70 nm. The XRD pattern indicates that the values of d(hkl), a, and unit cell volume (V-3) of Ag crystal are all a little greater than that of Ag standard card, with face-centred cubic structure. UV-visible spectra (UV-Vs) and liquid chromatography-mass spectrometry (LC-MS) was used to identify the product of oxidation of o-PD in solution after reaction. The results of UV-Vs and LC-MS illustrate that the product of oxidation of o-PD in solution is 2,3-diaminophenazine.

Abstract  An anode magnetron enhanced d.c. cathodic plasma treatment of a cold-rolled steel (CRS) plate and cathodic (plasma) polymerization were used to create interface engineered systems of cathodic E-coat/plasma polymer/plasma treated CRS. The adhesion of the E-coat and the corrosion protection characteristics of the systems were compared with the control, E-coat/Zn phosphate-chromate/electro-galvanized steel (EGS). The adhesion of the E-coat to the plasma polymer coated CRS was found to be excellent; the E-coat could not be removed by N-methyl pyrrolidone (60 degrees C) in 5 days, while the same E-coat applied on the control was removed in a few minutes. The plasma polymer of trimethylsilane (TMS) was found to yield excellent corrosion protection as used in the interface engineered systems, of which the corrosion (GM scab) test was found to be better than that for the control. The plasma pretreatment of the CRS surface prior to the cathodic polymerization of TMS was found to be a critically important factor. The corrosion-induced delamination of the first paint layer seems to play a key role in the corrosion of painted steel. Tt was demonstrated that good adhesion and durability of the entire interface system can produce a highly corrosion resistant painted CRS.

Abstract  Pt skin growth over PdPt alloy nanocrystals has been described using a simple wet chemical method, where a layer-by-layer epitaxial deposition of Pt on PdPt could be understood by the Stranski-Krastanov mechanism. Initial PdPt alloy nanocrystals grown in a simple wet-chemical method, in the presence of a reducing solvent like N-methyl pyrrolidone (NMP) and a stabilizer like polyvinyl pyrrolidone (PVP), have been used as the substrate for secondary growth of a Pt thin layer. Surface changes have been observed during step-by-step growth of polyhedral Pt skin@PdPt nanocrystals originating from nearly octahedral geometries of PdPt. The methanol electrooxidation activities of two different Pt skin@PdPt nanostructures have been compared with PdPt nanocrystals with similar compositions but without skin structures and commercial RuPt catalysts. A gain factor of 8 towards electrooxidation of methanol in acidic media with activities of 1950 mA mg(Pt)(-1) and 3.1 mA cm(Pt)(-2) (with lower onset potential compared to the RuPt commercial catalyst), which is believed to be much higher compared to that of previous reports and state-of-art RuPt/C catalysts, indicating better surface properties and core-alloy formation along with improved intraparticle active interfacial sites. Additionally, exciting results of electrooxidation of ethanol and ethylene glycol with 70% and 58% activity retention respectively, after 5000 cycles are also found, demonstrating a facile C-C breaking in such C2 type alcohols.

Abstract  New polyethers with pendant chloromethyl groups were successfully synthesized by a polyaddition of bisepoxides with 4,4'-dichloro-3,3'-dinitrodiphenyl sulfone (DCNS) using quaternary onium salts or crown ether complexes as catalysts. The polyaddition of DCNS with diglycidyl ether of bisphenol A (DGEBA) was enhanced efficiently by the addition of tetrabutylammonium chloride (TBAC), tetrabutylammonium bromide (TBAB), or tetrabutylphosphonium chloride (TBPC) as catalysts. It was also found that the reaction proceeded smoothly in amide-type polar solvents such as N,N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) to give a high molecular weight polyether P-1. The polyaddition of DCNS with diglycidyl ether of ethylene glycol (DGEEG) using TBAB in DMAc also proceeded to give the polyether P-2 in good yield. The resulting polyethers contain reactive chloromethyl groups in a side chain, which was introduced during main chain formation.

Abstract  Nylon-6/epoxy resin composite with multiphase morphology has been successfully prepared via polymerization of caprolactam in N-methylpyrrolidone using N-acetyl caprolactam as the initiator. This was followed by reactive blending of appropriate amount of the plastic with epoxy resin. The structure of nylon-6 prepared by solution polymerization is predominantly [200, 020] crystalline form with [002] crystalline form as the minor phase. Subsequently, nylon-6/epoxy composite was prepared at 150 degrees C in a Teflon mold. A remarkable heterogeneous morphology of the fractured surface of the film was observed, consisting of multilayered fiber-like crystals encapsulated in the epoxy resin matrix. Close inspection of the morphology of the composite revealed a preference of nylon-6 to crystallize in the crevices and cracks created in glassy epoxy matrix during processing. The crystals seem to nucleate spontaneously and grow radially into spherulites. POLYM. ENG. SCI., 54:858-866, 2014. (c) 2013 Society of Plastics Engineers

Abstract  The copolymers of N-vinyl-2-pyrrolidone (N-VP) and condensation cardo and/or fluorinated condensation polymers (aromatic polyamide, polyimide and polyarylate) were-synthesized by free radical in situ polymerization. The partial formation (14-61 wt%) of polivnylpyrrolidone (PVP) homopolymer upon the polymerization of N-VP containing dissolved condensation polymer was stated. Synthesized (co)polymers are differed in heat resistance and solubility from neat PVP. Using relevant copolymers solutions in N-methyl-2-pyrrolidone the optical fiber coatings having good adhesion properties were fabricated. Such coatings demonstrate high stability at elevated temperatures. A substantial number of defects on coatings and a slight decrease in bending strength are observed only on exposure at 200 degrees C for 72 h. Simultaneously holding for 1 and 24h at the same temperature leads to hardening of the fibers: bending strength changes from similar to 5 up to 6 GPa. (C) 2016 Elsevier B.V. All rights reserved.