Cerium ion-exchanged layered MCM-22: preparation,characterization and its application for esterification of fatty acids

A series of cerium ion-exchanged MCM-22 catalysts was prepared by post-synthetic ion-exchange route. The resultant cerium-exchanged MCM-22 zeolite was systematically characterized using FTIR, powder X-ray diffraction (XRD), N₂ adsorption and desorption analysis, scanning electron microscopy, thermogravimetric analysis and diffuse reflectance UV–Vis spectral studies. The XRD pattern and FTIR data confirmed the MCM-22 structure. The diffuse reflectance UV–Vis spectroscopy showed coordination nature of the cerium ions. The cerium exchange MCM-22 zeolite showed promising activity for the esterification of fatty acids, achieving a maximum conversion of 75% at 70 °C in 24 h. Importantly the catalytic activity increases upon recycle due to hydrophic nature of recycled catalyst.     

Synthesis and characterization of novel poly(aniline-co-m-aminoacetophenone) copolymer nanocomposites using dodecylbenzene sulfonic acid as a soft template

A series of dodecylbenzene sulphonic acid (DBSA) doped poly(aniline-co-m-aminoacetophenone) copolymer composites of different compositions were synthesized in micellar solution of DBSA to obtain nanosphere morphology with enhanced processability. The plausible mechanism for the formation of poly(aniline-co-m-aminoacetophenone)-DBSA copolymer composite has been presented. These DBSA doped copolymer composites were characterized by UV–Visible, FTIR spectroscopy and XRD analysis techniques. UV–Vis absorption spectrum of the composites showed 325 and 637 nm which corresponds to the π–π* and n–π* transition. In FTIR spectroscopy a broad band around 2,924 cm^?1 corresponds to C–H vibration of DBSA indicating good agreement with the characteristic bands of DBSA. The sharp band at 1,292 cm^?1 is assigned to C–N stretching mode of vibration of N–Ph–N units. The X-ray diffraction of composites reveals that these composites are amorphous in nature. The number of diffraction peaks decreased with increase in the m-aminoacetophenone content. It indicates that these composites are amorphous in nature. Morphological studies (SEM) reveal that these composites have a spherical morphology with the average size of 100–200 nm. These composites exhibit electrical conductivity value of 0.744 × 10^?3 S/cm and enhanced solubility than polyaniline. Moreover, at the presented work, the DBSA doped copolymer composites were obtained in high yields by keeping an oxidant to co-monomer ratio of 1:1.     

Mg Doped Copper Ferrite with Polyaniline Matrix Core–Shell Ternary Nanocomposite for Electromagnetic Interference Shielding

Electromagnetic interference shielding materials based on polyaniline/Mg_0.6Cu_0.4Fe₂O₄ ternary nanocomposites were prepared using in situ chemical oxidation polymerization method. The crystalline, structural and morphology analyses of the synthesized material were studied by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR) and high resolution transmission electron microscopy (HR-TEM). The nanocomposites were examined by UV–Vis spectroscopy (UV–Vis), four probe resistivity, vibrating sample magnetometer (VSM), thermal gravimetric analysis (TGA) and vector network analyzer (VNA) for the optical, electrical, thermal, magnetic and shielding properties. XRD, FTIR and UV–Vis spectra analyses confirmed the formation of ferrites and polyaniline phases in the composites. The particle sizes of Mg_0.6Cu_0.4Fe₂O₄ are lying in the range of 15–40 nm verified by the HR-TEM. VSM study proved the presence of magnetic nanoparticles in the polyaniline matrix. TGA results revealed that the mixing of ferrites particles in polyaniline has improved its thermal stability. The nanocomposites are showing the significant shielding effectiveness value up to 32.8 dB in the X-band frequency range which makes them potential shielding material for electromagnetic interference shielding applications due to lightweight, good processability and low cost.     

Investigation of structure and conductivity properties of polyaniline synthesized by solid–solid reaction

Conductive polyaniline has been prepared by solid–solid reaction using ammonium peroxydisulfate as an oxidant. The obtained polymer was examined by X-ray diffraction, UV visible, FTIR spectroscopy, thermogravimetric analysis and impedance spectroscopy. The effect of oxidant/monomer molar ratio (R) on the structure and electrical properties of polymer has been examined. The analyses of X-ray diffraction patterns demonstrated that polyaniline prepared by this method is more crystalline than that obtained by conventional solution method. The FTIR spectroscopy showed that the emeraldine salt has been formed. The electrical properties were measured at different temperatures in the range of 296–523 K. The ac conduction shows a regime of constant dc conductivity at low frequencies and a crossover to a frequency-dependent regime of the type A ω^S at high frequencies.     

Characterization and AC conductivity of polyaniline–montmorillonite nanocomposites synthesized by mechanical/chemical reaction

Polyaniline–clay nanocomposites were prepared by solid state polymerization of aniline chloride in the interlayer of montmorillonite through the use of persulfate of ammonium as oxidant. The proportion of aniline to clay and the molar ratio of oxidant to aniline are being varied. The analyse of UV visible and FTIR spectroscopy demonstrated that aniline has been polymerized to polyaniline (PANI) in its conducting emeraldine form. The conformation adopted by PANI chains in the clay interlayer depended on the molar ratio of aniline to montmorillonite. Thermogravimetric analysis of the nanocomposites suggested that polyaniline chains are more thermally stable than those of free polyaniline prepared by solid–solid reaction. The AC conductivity data of different synthesized nanocomposites were analyzed as a function of frequency. Low frequency conductivities of polyaniline/montmorillonite nanocomposites materials ranges from 0.18 to 5.6 × 10^?3 S/cm. All characterization data were compared to those of free polyaniline that was synthesized using a solid–solid reaction.     

Structural,Morphological, Optical,and Electrical Properties of PANi-ZnO Nanocomposites

Thin films of polyaniline (PANi) and PANi–Zinc oxide (ZnO) nanocomposites have been synthesized by a spin-coating technique. The ZnO powder of particle size 50–60 nm was synthesized by sol–gel technique and the polyaniline was synthesized by chemical oxidative polymerization of aniline. The nanocomposite films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), UV–Vis spectroscopy, and four probe technique, and the results were compared with polyaniline films.     

Synthesis,structural and optical properties of ZnS,CdS and HgS nanoparticles from dithiocarbamato single molecule precursors

Dithiocarbamate complexes of Zn(II), Cd(II) and Hg(II) were synthesize and characterized by elemental analysis, thermogravimetric analysis, UV–Vis, FTIR, ¹H- and ¹³C-NMR spectroscopy. The complexes were thermolyzed at 180°C to prepare HDA-capped ZnS, CdS and HgS nanoparticles. The optical properties of the nanoparticles showed absorptions that are blue shifted with respect to the bulk and narrow emissions. The ZnS nanoparticles are in the cubic phase with average crystallite sizes of 3–5 nm. The CdS nanoparticles consist of a mixture of cubic and hexagonal phases with particle sizes of 8–22 nm, while the HgS nanoparticles are in the cubic phase with average crystallite sizes of 7–14 nm.     

Waterborne acrylic–polyaniline nanocomposite as antistatic coating: preparation and characterization

An antistatic and electrically conductive acrylic–polyaniline nanocomposite coating was successfully synthesized by interfacial polymerization of aniline in the presence of acrylic latex. The acrylic latex was prepared through emulsion polymerization, and aniline was polymerized by in situ interfacial polymerization at the interface of acrylic latex/chloroform phase. Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy and CHNS elemental analysis revealed the existence of 6.24 wt% emeraldine salt of polyaniline (PAni) in the dried film of the nanocomposite. Scanning electron microscopy (SEM) confirmed the presence of colloidal polymer particles in the aqueous phase which was confirmed to have some advantages, including prevention of aggregation of particles, dispersibility improvement and enhancement of the PAni nanofibers aspect ratio in the acrylic polymer matrix. According to SEM results, PAni fibers with the length ranging from 12 to 67 µm and diameters between 0.078 and 1 µm, highly dispersed in the acrylic polymer matrix, were successfully synthesized. Thermal, electrical and mechanical properties of the acrylic copolymer were significantly affected by PAni incorporation. The onset degradation temperature in thermogravimetric analysis revealed that the thermal stability of the nanocomposite was improved compared to that of the pure acrylic copolymer. The nanocomposite film showed electrical conductivity of about 0.025 S/cm at room temperature, along with satisfactory mechanical properties, attractive as an antistatic material in coating applications.     

Synthesis of conducting polyaniline/TiO2 composite nanofibres by one‐step in situ polymerization method

Conducting polyaniline (PANI)/titanium dioxide (TiO₂) composite nanofibres with an average diameter of 80–100 nm were prepared by one‐step in situ polymerization method in the presence of anatase nano‐TiO₂ particles, and were characterized via Fourier‐transform infrared spectra, UV/vis spectra, wide‐angle X‐ray diffraction, thermogravimetric analysis, and transmission electron microscopy, as well as conductivity and cyclic voltammetry. The formation mechanism of PANI/TiO₂ composite nanofibres was also discussed. This composite contained ～ 65% conducting PANI by mass, with a conductivity of 1.42 S cm^?1 at 25°C, and the conductivity of control PANI was 2.4 S cm^?1 at 25°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Polyhydrosilane Mediated Synthesis of One-Dimensional Gold Nanostructures

This work presents a solution-phase approach for the “one pot” synthesis of polysilane-gold nanorods. The process starts by the reduction of HAuCl₄ to Au^o with a solution of poly[diphenylsilane-co-methyl(H)silane] cooled to 4 °C. The formed small Au nanoparticles (5–15 nm diameter) serve further as seeds for the heterogeneous nucleation and anisotropic growth that takes place at 25 °C and yields crystalline needle-like polymer–gold nanostructures. The evolution of the small spherical nanoparticles to nanorods with length/width aspect ratios up to 10³ has been proved by UV–Vis spectroscopy, polarized light microscopy and AFM. Further insights on the growth mechanism were obtained by SEM, DLS and TEM.     

CuO Impregnated mesoporous silica KIT-6: a simple and efficient catalyst for benzene hydroxylation by C–H activation and styrene epoxidation reactions

Copper oxide doped mesoporous KIT-6 materials were synthesized by ultrasonication as impregnation method. The highly ordered nature of mesoporous CuO-KIT-6 materials analyzed by low angle X-ray diffraction. The high surface area, pore diameter and mesoporous nature of synthesized materials were confirmed by BET surface area analysis. Si–O–Si, Si–OH and Cu–O–Si bonds in the framework of CuO-KIT-6 were verified by FTIR spectroscopy. The Cu²⁺ ← O^2? charge-transfer transitions and d–d transitions of dispersed Cu²⁺ on ordered mesoporous KIT-6 were identified by DRS UV–Vis spectroscopy. The morphology of the synthesized CuO-KIT-6 materials was analyzed by HR-SEM. The 3D ordered nature of CuO-KIT-6 confirmed by TEM analysis. The highly ordered 3D mesoporous CuO-KIT-6 materials are excellent catalyst for benzene hydroxylation reaction through C-H activation and styrene epoxidation reaction with 30 % aqueous H₂O₂. The catalyst CuO-KIT-6 itself showed a good conversion towards both reactions.     

Dielectric Investigation of NaLiS Nanoparticles Loaded on Alginate Polymer Matrix Synthesized by Single Pot Microwave Irradiation

Sodium lithium sulfide (NaLiS) nanocomposite have been successfully synthesized by using microwave-irradiation (MWI) method. The study suggested that the application of microwave heating is to produce homogeneous and fine NaLiS nanocomposite which were achieved by using the precursors of lithium acetate and thioacetamide in the presence of sodium alginate biopolymer. FTIR is used to identify the structural coordination and functional groups of the prepared nanocomposite. The structural property of NaLiS particles was investigated by XRD. The surface morphology and elemental composition of synthesized material was confirmed by SEM and EDX analyses. The optical property was studied by using UV–Vis spectrophotometer. Thermal stability of as prepared sample was studied by TGA/DTG analysis. Electrical transport studies of the prepared nanocomposite have been analyzed for various temperatures. NaLiS nanocomposite has ionic conductivity of ~?10^?7 S cm^?1 at 35 °C which is six orders of magnitude higher than that of micro sized bulk Li₂S (~?10^?13 S cm^?1).     

Electrochemical synthesis of poly(2‐iodoaniline) and poly(aniline‐co‐2‐iodoaniline) in acetonitrile

Poly(2‐iodoaniline) (PIANI) and poly(aniline‐co‐2‐iodoaniline) [P(An‐co‐2‐IAn)] were synthesized by electrochemical methods in acetonitrile solution containing tetrabutylammonium perchlorate (TBAP) and perchloric acid (HClO₄). The voltametry of the copolymer shows characteristics similar to those of conventional polyaniline (PANI), and it exhibits higher dry electrical conductivity than PIANI and lower than PANI. The observed decrease in the conductivity of the copolymer relative to PANI is attributed to the incorporation of the iodine moieties into the PANI chain. The structure and properties of these conducting films were characterized by FTIR and UV‐Vis spectroscopy and by an electrochemical method (cyclic voltametry). Conductivity values, FTIR and UV‐Vis spectra of the PIANI and copolymer were compared with those of PANI and the relative solubility of the PIANI and the copolymer powders was determined in various organic solvents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1652–1658, 2003     

A study on polymer blend electrolyte based on PVA/PVP with proton salt

Proton-conducting polymer blend electrolytes based on PVA–PVP–NH₄NO₃ were prepared for different compositions by solution cast technique. The prepared films are investigated by different techniques. The XRD study reveals the amorphous nature of the polymer electrolyte. The FTIR and laser Raman studies confirm the complex formation between the polymer and salt. DSC measurements show decrease in T _g with increasing salt concentration. The ionic conductivity of the prepared polymer electrolyte was found by ac impedance spectroscopy analysis. The maximum ionic conductivity was found to be 1.41 × 10^?3 S cm^?1 at ambient temperature for the composition of 50PVA:50PVP:30 wt% NH₄NO₃ with low-activation energy 0.29 eV. The conductivity temperature plots are found to follow an Arrhenius nature. The dielectric behavior was analyzed using dielectric permittivity (ε*) and the relaxation frequency (τ) was calculated from the loss tangent spectra (tan δ). Using this maximum ionic conducting polymer blend electrolyte, the primary proton battery with configuration Zn + ZnSO₄·7H₂O/50PVA:50PVP:30 wt% NH₄NO₃/PbO₂ + V₂O₅ was fabricated and their discharge characteristics studied.     

Metalphthalocyanines Anchored Poly(1,3,4-oxadiazole arylene ether)s: Optical and Electrical Studies

New phenolphthalein based poly(1,3,4-oxadiazole aryl ether) (PHOP) containing side chain carboxylic acid groups derived from 2,5-bis(4-fluorophenyl)-1,3,4-oxadiazole and 2-(bis(4-hydroxyphenyl)methyl)benzoic acid have been synthesized from typical aromatic nucleophilic substitution reaction. The PHOP seizes high dielectric constant (300 at 50 Hz) by the assistance of polar pendants and its findness in advance studies needs some structure modification with high dielectric constant metalphthalocyanine (MPc, M=Co, Ni & Cu) macrocycle to come out as further enhancement of dielectric constant and become photoactive polymer embedded metalphthalocyanine (PPEMP1–9). The molecular weight of PHOP was determined by gel permeation chromatography and is found to be 33375 (M _w/M _n = 2.48). All the tailor-made polymers were well characterized by Solid State UV–Vis, thermogravimetric analysis and XRD analysis. FTIR and NMR spectroscopic techniques confirms MPc units are grafted into the polymer matrix and act as a utmost light catching materials in the visible to near IR region (400–900 nm) with remarkable drop off in optical band gap and exhibited impressive thermal properties. The variation in the AC conductivity was explained by electron hopping model and values are in the range of 3.16 × 10^?5–4.78 × 10^?5 (S/m) at 5 MHz measured at 20 °C.     

The Preparation of Phosphazene Crosslinked Cyclen Microspheres as Host for Cu<Superscript>2+</Superscript> Ions and Their Utilization as a Support Material for the Preparation of a Copper Nanocatalyst

In this study firstly, phosphazene crosslinked cyclen microspheres were synthesized. Then, supported copper nanoparticles were prepared on these phosphazene crosslinked cyclen microspheres for use as a metal catalyst. The prepared microparticles and microparticle-supported metal catalyst were characterized using FT-IR, SEM-EDX, TEM and XPS analysis. Also, the prepared metal composite was used as a catalyst for the reduction reaction of 4-nitrophenol in the presence of NaBH₄ in aqueous media. The catalytic activity of the Cu-cyclen composite catalyst was investigated using UV–Vis spectroscopy. The reduction studies were completed at four different temperatures (30–60?°C). The activation parameters were calculated from the obtained rate constants at the four different temperatures (30–60?°C). The activation energy, activation enthalpy and activation entropy for the reduction reaction of 4-NP in the presence of Cu-cyclen composite catalyst were calculated as 39.88, 36.56 and ?143.30 kJmol^?1, respectively. The total turnover frequency (TOF) for Cu-cyclen composite catalyst was 0.794 mol 4-NP (mol Cu)^?1 (min)^?1.     

Eco-Friendly Electromagnetic Interference Shielding Materials from Flexible Reduced Graphene Oxide Filled Polycaprolactone/Polyaniline Nanocomposites

Hybrid nanocomposites have the unique ability of enhancing material properties due to the existing synergistic effect of the fillers. In this study, the authors report such an eco-friendly hybrid nanocomposite comprising of polyaniline and reduced graphene oxide in polycaprolactone. The conducting polyaniline improved the processability of polycaprolactone, and the final composites were prepared by incorporating graphene oxide reduced at 200 and 600°C temperatures to the polycaprolactone–polyaniline blend. Polyaniline, polyaniline/reduced graphene oxide200, and polyaniline/reduced graphene oxide600 imparted good electrical conductivity to polycaprolactone, and the fabricated flexible polycaprolactone–polyaniline/reduced graphene oxide nanocomposites exhibited good mechanical property, increased thermal stability, and excellent electromagnetic interference shielding up to 42 dB at 13 GHz.     

Conductive composites from polyaniline and polyurethane sulphonate anionomer

The present work describes the synthesis of conductive composite of polyurethane sulphonate anionomer (PUSA) and para toluene sulphonic acid doped polyaniline (PANI–PTSA). HCl‐doped PANI was synthesized by chemical oxidative polymerization of aniline in HCl, which was converted to PANI–EB by treatment with NH₄OH. PTSA doped PANI was synthesized from EB‐PANI by redoping with PTSA solution. PUSA was synthesized from 4, 4′‐diphenylmethanediisocyanate (MDI), polypropylene glycol (PPG), 1,4‐butanediol (BD), and ionic diol SDOL. The composite was prepared by mixing of the solutions of two polymer components in DMF and then solution casting. The products were characterized and analyzed by UV‐Vis and FTIR spectroscopy, thermogravimetry, differential scanning calorimetry and scanning electron microscopy. The conductivity was found to increase by 100 times with concomitant decrease in percolation threshold when polyurethane was replaced by PUSA in the composite for the same amount of polyaniline. The composite film was thermally stable upto ～300°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41600.     

Synthesis of exfoliated conductive polyaniline–graphite nanocomposites in supercritical CO2

Exfoliated polyaniline–graphite nanocomposites with high electrical conductivity were synthesized. Graphite powders were first expanded with ScCO₂ treatment and then aniline monomers were added to the suspension. The morphology and structure of the synthesized products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV/Vis spectroscopy and XRD analysis. SEM and TEM micrographs revealed that graphite was successfully expanded through ScCO₂ treatment, and the graphite powders are fully exfoliated in the final nanocomposite. FTIR results confirmed formation of polyaniline (PANI), and UV/Vis analysis showed the conductive emeraldine state of the synthesized PANI. Furthermore, it was clearly demonstrated that ScCO₂ medium does not have any effect on chemical structures of the PANI. The electrical conductivities of the PGNs enhanced dramatically with increasing graphite loading up to 40% and subsequently decreased due to the weaker bridged linkage between PANI and graphite layers at high graphite loading.     

Preparations,optical, structural,conductive and magnetic evaluations of RE's (Pr,Y, Gd,Ho, Yb) doped spinel nanoferrites

Rare earths RE's (Pr, Y, Gd, Ho, Yb) substituted MnZn spinel ferrites with composition of Mn_0.5Zn_0.5M_0.02Fe_1.98O₄ (M = Pr, Y, Gd, Ho, Yb) are prepared by sol gel combustion approach. Low sintering temperature (500 °C) is used to sinter the RE's doped MnZn samples. MnZn samples are further characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) to measure the cubic crystalline structure, particle size, morphology, porosity and grain size. Cubic crystalline phase of prepared RE's doped MnZn ferrites is confirmed by x-ray diffraction (XRD). The morphology, porosity and grain size are observed using FESEM. The magnetic properties of RE's doped MnZn nanoferrites are analyzed by vibrating sample magnetometer (VSM). Coercivity (H_c), remanence (M_r) and saturation magnetization (M_s) are calculated from the magnetic loops. The saturation and remanence of the nanoferrites are increased by the substitution of RE's metal ions and varies from 14.76 to 26.36 emu/g and 9.98–22.48 emu/g respectively. Bohr magneton and anisotropy constant are calculated from the recorded magnetic data. The conductive analysis of the prepared samples is studied at 40 °C −300 °C temperature, leading to the conductivity measurements from 1.12 × 10^-2 Ω^-1-cm^-1 to 9.52 × 10^-2 Ω^-1-cm^-1. UV–Vis spectroscopy is used to determine the semi conducting nature of RE's doped MnZn spinel ferrite samples. The magnetic, conductive and optical study of the RE's doped MnZn nanoferrites sintered at low temperature suggests the use of these materials for microwave absorption, supercapacitor, lithium ion batteries and nanoelectronics industrial applications.