XPS studies of Ni deposition on polymethyl methacrylate and poly(styrene‐co‐acrylonitrile)

Thin Ni layers were deposited onto clean polymethyl methacrylate (PMMA) and poly(styrene‐co‐acrylonitrile) (SAN) surfaces by a high vacuum thermal evaporation process. The resulting interfaces were studied by X‐ray photoelectron spectroscopy. The Ni deposition on PMMA changes the relative intensity of the C1s spectra associated with the O CO and C O carbon species, and modifies the shape of the O1s peak, while the Ni evaporation on SAN alters the C1s band intensity assigned to the CN moiety and gives a second N1s band at low binding energies. These observations suggest the formation of new chemical species at the interface between Ni and the PMMA ester group, and between Ni and the SAN nitrile group, which are the most reactive sites on these two polymers. Copyright © 2000 John Wiley & Sons, Ltd.     

Copper(ii) ketimides in sp3 C–H amination

Commercially available benzophenone imine (HN CPh₂) reacts with β-diketiminato copper(ii) tert-butoxide complexes [Cu^II]–O^tBu to form isolable copper(ii) ketimides [Cu^II]–N CPh₂. Structural characterization of the three coordinate copper(ii) ketimide [Me₃NN]Cu–N CPh₂ reveals a short Cu-N_ketimide distance (1.700(2) Å) with a nearly linear Cu–N–C linkage (178.9(2)°). Copper(ii) ketimides [Cu^II]–N CPh₂ readily capture alkyl radicals R˙ (PhCH(˙)Me and Cy˙) to form the corresponding R–N CPh₂ products in a process that competes with N–N coupling of copper(ii) ketimides [Cu^II]–N CPh₂ to form the azine Ph₂C N–N CPh₂. Copper(ii) ketimides [Cu^II]–N CAr₂ serve as intermediates in catalytic sp³ C–H amination of substrates R–H with ketimines HN CAr₂ and ^tBuOO^tBu as oxidant to form N-alkyl ketimines R–N CAr₂. This protocol enables the use of unactivated sp³ C–H bonds to give R–N CAr₂ products easily converted to primary amines R–NH₂via simple acidic deprotection.

Commercially available benzophenone imine (HN CPh₂) reacts with β-diketiminato copper(ii) tert-butoxide complexes [Cu^II]–O^tBu to form isolable copper(ii) ketimides [Cu^II]–N CPh₂ that serve as intermediates in catalytic sp³ C−H amination via radical relay.     

An Investigation into the PVA:MC:NH4Cl-Based Proton-Conducting Polymer-Blend Electrolytes for Electrochemical Double Layer Capacitor (EDLC) Device Application: The FTIR,Circuit Design and Electrochemical Studies

In this report, the preparation of solid polymer electrolytes (SPEs) is performed from polyvinyl alcohol, methyl cellulose (PVA-MC), and ammonium chloride (NH₄Cl) using solution casting methodology for its use in electrical double layer capacitors (EDLCs). The characterizations of the prepared electrolyte are conducted using a variety of techniques, including Fourier transform infrared spectroscopy (FTIR), electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). The interaction between the polymers and NH₄Cl salt are assured via FTIR. EIS confirms the possibility of obtaining a reasonably high conductance of the electrolyte of 1.99 × 10⁻³ S/cm at room temperature. The dielectric response technique is applied to determine the extent of the ion dissociation of the NH₄Cl in the PVA-MC-NH₄Cl systems. The appearance of a peak in the imaginary part of the modulus study recognizes the contribution of chain dynamics and ion mobility. Transference number measurement (TNM) is specified and is found to be (t_ion) = 0.933 for the uppermost conducting sample. This verifies that ions are the predominant charge carriers. From the LSV study, 1.4 V are recorded for the relatively high-conducting sample. The CV curve response is far from the rectangular shape. The maximum specific capacitance of 20.6 F/g is recorded at 10 mV/s.     

Designing of Zn (II)-based novel coordination polymer (CP): Synthesis,characterization, and heavy metal removal from water

A new coordination polymer, Zn-(OC-AMAM-CO) CP, has been synthesized from Zn (II) as ionic node and 2,2′-((1,2-phenylenebis [azanediyl])bis (carbonyl))dibenzoic acid, (OC-AMAM-CO), as a new linker, where (OC-AMAM-CO) has been synthesized as an amide product through condensation reaction of phthalic acid and o-phenylenediamine. The amide product (OC-AMAM-CO) and Zn-(OC-AMAM-CO) CP were characterized via FTIR and PXRD analyses, and Zn-(OC-AMAM-CO) CP was further characterized via SEM/EDX and XPS analyses. Moreover, DFT study was performed to shed light on the both structures of (OC-AMAM-CO) and Zn-(OC-AMAM-CO). PXRD analysis revealed the successful syntheses of the new linker (OC-AMAM-CO) and Zn-(OC-AMAM-CO) CP where the new CP is crystalline. DFT study revealed that the 3D topological structure assembled through coordination, π–π stacking, and hydrogen bonding. Zn-(OC-AMAM-CO) CP was applied as an adsorbent for the removal of Cu (II) from water as it has abundant chelating groups that serve as adsorptive coordinating sites. Isotherm study revealed the obedience of Cu (II)/Zn-(OC-AMAM-CO) CP adsorption system to Langmuir modeling with adsorption capacity of about 55 mg/g. A kinetic study showed that the rate of adsorption was a pseudo-first-order type. Further, adsorption process was found to be strongly diffusion dependent.     

Investigation of the curing kinetics of polyurethane/nitrocellulose blends through FT-IR measurements

Polyester (HTPS) based polyurethane (PU) elastomers were currently established to be effective binders for high-energy composites with improved performances. Conventional PU binders are mostly non-energetic materials, and consequently reduce the energy performance significantly. Nitrocellulose (NC), is an energetic polymer widely used as an ingredient in propellants, explosives, fireworks, and gas generators, it may be introduced in PU-based compositions to overcome their performance drawback. Kinetic parameters must be specified in order to build PU binders with the most convenient and appropriate features. Therefore, the cure kinetics of polyester based polyurethane binder systems were investigated by Fourier transform infrared spectroscopy (FT-IR) isothermal method. The polyester prepolymer (Desmophen^® 1200) was cured with hexamethylene diisocyanate (HDI: Desmodur^® N100) at various molar ratios (R_[NCO]/[OH] = 0.6, 1, 1.25, and 1.5) and under different isothermal conditions (T = 60°C, 80°C, 100°C, and 120°C). In addition, the effect of the addition of nitrocellulose on the kinetics of polymerization of PU was investigated. The progression of the reaction was followed based on the decrease of the peak intensity of –NCO group at 2271 cm⁻¹ as a function of the reaction time. The curing kinetic model and the apparent activation energy (E_α) were determined by the use of Kamal autocatalytic model and Friedman isoconversional method, respectively.     

Synthesis and study of poly(ethylene oxide) membranes obtained from homopolymerization of peo macromonomers

Hydrogels were obtained by free-radical polymerization of bifunctional macromonomers. This reaction can be conducted in water solution or in organic solvent. The k_p value is yet strongly depending on the solvent used. The properties of these networks will be compared to those of networks obtained by end-linking procedures. These materials were also used as a semi-permeable membrane in the conception of an artificial pancreas.