Grafting of poly(styrene‐co‐p‐chloromethyl styrene) with ethyl methacrylate via atom transfer radical polymerization catalyzed by CuCl/1,2‐dipiperidinoethane

Poly(styrene‐graft‐ethyl methacrylate) graft copolymer was prepared by atom transfer radical polymerization (ATRP) with poly(styrene‐co‐p‐chloromethyl styrene)s in various compositions as macroinitiator in the presence of CuCl/1,2‐dipiperidinoethane at 130 °C in N,N‐dimethylformamide. Both macroinitiators and graft copolymers were characterized by elemental analysis, IR, ¹H and ¹³C NMR, and differential scanning calorimetry. 1,2‐Dipiperidinoethane was an effective ligand of CuCl for ATRP in the graft copolymerization. The controlled growth of the side chain provided the graft copolymers with polydispersities of 1.60–2.05 in the case of poly(styrene‐co‐p‐chloromethyl styrene) (62:38) macroinitiator. Thermal stabilities of poly(styrene‐graft‐ethyl methacrylate) graft copolymers were investigated by thermogravimetric analysis as compared with those of the macroinitiators. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 668–673, 2003     

Heterobimetallic Nickel(II) Complexes of Ferrocenyldithiophosphonates. Molecular Structures of [{FcP(OR)S2}2Ni] [Fc = Fe(η5‐C5H4)(η5‐C5H5), R = Et,Pri, Bus,Bui]

The reaction of 2,4‐diferrocenyl‐1,3‐dithiadiphosphetane 2,4‐disulfide [FcPS(μ‐S)]₂ [Fc = Fe(η⁵‐C₅H₄)(η⁵‐C₅H₅)] with alcohols ROH gave the corresponding ferrocenyldithiophosphonic acids [FcPS(OR)(SH)], which were treated in situ with Ni(CH₃COO)₂·4H₂O in acetic acid to yield the square‐planar heterobimetallic trinuclear complexes [{FcP(OR)S₂}₂Ni] (R = Me ( 1 ), Et ( 2 ), Prⁱ ( 3 ), Bu^s ( 4 ) and Buⁱ ( 5 )). Compounds 1‐5 were characterized by elemental analysis, MS, NMR (¹H, ¹³C and ³¹P), IR spectroscopy, and 2‐5 also by X‐ray crystallography. Cyclovoltammetric studies on the heterobimetallic nickel(II) complexes 1‐5 showed irreversible reduction to unstable nickel(I) complexes and an irreversible two‐electron oxidation of the sulfur‐containing nickel fragments, followed by a reversible one‐electron oxidation of the two ferrocenyl groups.     

A stopping rule for a compound poisson random variable

An optimal empirical Bayesian stopping rule for the Poisson compounded with the geometric distribution is developed and applied to the problem of the sequential testing of computer software. For each checkpoint in time, either the software satisfies a desired economic criterion, or else the software testing is continued.     

Synthesis and X-ray crystal structure determination of N-p-methylphenyl-4-benzoyl-3,4-diphenyl-2-azetidinone

The title compound, C₂₉H₂₃NO₂, has been characterized by single-crystal X-ray diffraction at two different temperatures (303 K and 120 K) and wavelengths (MoK _α and CuK _α). The non-centrosymmetric hexagonal crystal structure contains four-membered planar β-lactam ring with an unusually long C-C bond. The β-lactam ring is almost planar.     

Average 2p subshells fluorescence yield values of some elements in the atomic number range 60 ≤ Z ≤ 90

The average 2p (L_2,3) subshells fluorescence yield (?_2,3) in 11 elements with Z ranging from 60 to 90 were measured with corporation of total L_2,3 X-ray production cross-sections. Measurements were carried out exciting L₂ and L₃ subshells of relevant elements that were exposed to beam of selected K X-rays from secondary sources. The measured values were compared with theoretical and semi-empirical values. It is clear that the present values of experimental ?_2,3 are generally smaller than the calculated and semi-empirical values for some elements in the atomic number range 60–90.     

Thermal degradation of two different polymers bearing amide pendant groups prepared by ATRP method

Piperidinocarbonylmethyl methacrylate (PyCMMA) and 1-(piperidinocarbonyl) ethylmethacrylate (PyCEMA) monomers were synthesized. Polymerizations of PyCMMA and PyCEMA were carried out by atom transfer radical polymerization. The structure of monomers and polymers was characterized by ¹H-NMR, ¹³C-NMR, and FT-IR spectroscopies. Characterization of poly(PyCMMA) and poly(PyCEMA) were carried out using differential scanning calorimetry and gel permeation chromatography. The experimental results showed that the reaction exhibited characteristics of controlled polymerization. The thermal degradation behaviors of poly(PyCEMA) and poly(PyCMMA) were studied using thermogravimetry and a single line vacuum system consisting of a degradation tube with a condenser for product collection. The poly(PyCEMA) and poly(PyCMMA) were heated from ambient temperature to 325 and 500 °C, respectively. The products of degradation were collected as a cold ring fraction (CRF). The CRFs of degradation were investigated by means of IR, ¹HNMR, and GC-MS. For the degradation of both polymers, the major products of CRFs are piperidinocarbonyl methanol and 1,2-dipiperidino,1-oxo ethane. The GC-MS, IR, and NMR data showed that depolymerization below 325 °C to the corresponding monomer was not prominantin the thermal degradation of poly(PyCMMA). The mode of thermal degradation including formation of the major products was identified.     

Dielectric and proton conductivity studies in organic electrolytes based on 2-perfluoroalkyl-ethyl-azides

Intrinsically proton conducting organic electrolytes based on 2-perfluoroalkyl-ethyl-azides were synthesized via 1,3 cycloaddition between 2-perfluoroalkyl-ethyl-azide and alkynes. FT-IR, elemental analysis and NMR methods were used to characterize the resulting organic electrolytes. Thermal properties were analyzed with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and the morphology of the organic electrolytes was studied with X-ray diffraction (XRD). The effect of chain length on proton conductivity was investigated with impedance spectrometer. Dielectric constant and electrical modulus formalisms were analyzed and the maximum proton conductivity was measured as 10⁻² mS/cm at 180 °C.     

The characterization of prepared organomontmorillonite (DEDMAM) and sorption of phenoxyalkanoic acid herbicides from aqueous solution

The montmorillonite has been subjected to modification through ion-exchange reaction by N,N'-didodecyl-N,N'-tetramethylethanediammoniumdiiodide (DEDMAI). The modified sample was studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The basal spacing of modified montmorillonite was determined as 28.72 A. The IR spectra of organomontmorillonite showed changes in C-H vibrations. The characterization of N,N'-didodecyl-N,N'-tetramethylethanediammonium montmorillonite (DEDMAM) and the adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4-dichlorophenoxybutyric acid (2,4-DB), 4-chloro-2-methylphenoxyacetic acid (MCPA), and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) on organomontmorillonite was studied as a function of the solution concentration. The adsorption energy (E) and adsorption capacity (qm) for phenoxyalkanoic acid herbicides adsorbing on organomontmorillonite (DEDMAM) were estimated using the Dubinin-Radushkevic (D-R) equation. These isotherms were modeled according to Freundlich and Dubinin-Radushkevic adsorption isotherms. The sorption of the herbicides on DEDMAM increased in order of MCPA<2,4-D<2,4-DB<2,4,5-T.