Preparation and properties of alkylated poly(styrene-graft-ethylene oxide)

Poly(styrene-graft-ethylene oxide), having alkyl chains (C₁₂ or C₁₈) on the polystyrene main chain or on the poly(ethylene oxide) (PEO) side chains, were synthesized. The main chain was alkylated by first ionizing amide groups in a styrene/acrylamide copolymer with tert-butoxide, and then using the amide anions as sites for reactions with 1-bromoalkanes. An excess of amide anions was used in the reaction, and the remaining anions were subsequently utilized as initiator sites for the anionic polymerization of ethylene oxide (EO). Synthesis of poly(styrene-graft-ethylene oxide) with alkylated side chains was accomplished by polymerization of EO onto the ionized styrene/acrylamide copolymer, followed by an alkylation of the terminal alkoxide anions with 1-bromoalkanes. The alkylated graft copolymers were structurally characterized by using elemental analysis, ¹H NMR, GPC, and IR spectroscopy. DSC analysis showed that only graft copolymers with PEO contents exceeding about 50 wt % and side chain crystallinities comparable to those of homo-PEO. Main chain alkylated graft copolymers generally had higher crystalinities, as compared to nonalkylated and side chain alkylated samples. The graft copolymers absorbed water corresponding to one water molecule per EO unit at low PEO contents. The water absorption increased progressively at PEO contents above 30 wt % for main chain alkylated samples and above 50 wt % for non-alkylated samples. © 1995 John Wiley & Sons, Inc.     

Grafting of polyesters from carbon whisker surface: Copolymerization of epoxides with cyclic acid anhydrides initiated by COOK groups introduced onto the surface

To modify the surface of carbon whisker (vapor-grown carbon fiber) the grafting of polyesters by use of potassium carboxylate (COOK) groups introduced onto the surface was investigated. The introduction of COOK groups onto the carbon whisker was achieved by the treatment of surface carboxyl groups with KOH aqueous solution. Untreated carbon whisker has no ability to initiate the polymerization. It was found that the anionic ring-opening alternating copolymerization of epoxides with cyclic acid anhydrides is successfully initiated by COOK groups on the carbon whisker surface. The corresponding polyester was grafted onto the surface based on the propagation of polymer from COOK groups introduced on the surface. The percentage of grafting of the polyester from styrene oxide and phthalic anhydride was determined to be 91.0%. The polymerization rate and percentage of grafting increased upon addition of crown ether. Furthermore, the rate of polymerization increased with increasing the dielectric constant of the solvent, but the percentage of grafting decreased. Polyester-grafted carbon whisker was found to give a stable colloidal dispersion in a good solvent for the grafted polymer. © 1993 John Wiley & Sons, Inc.     

Molecular Recognition of Anionic Substrates. Crystal Structures of the Supramolecular Inclusion Complexes of Terephthalate and Isophthalate Dianions with a Bis-intercaland Receptor Molecule

Molecular recognition of flat substrates requires the design of receptor molecules containing complementary flat units. If two such units are incorporated into a macrocyclic framework, a face to face inclusion of a planar substrate may take place, leading to an intercalative supramolecular structure. The water-soluble macrocyclic bis-intercaland receptor 1.4H+, containing two naphthalene subunits, linked by two positively charged oxy-bis- ethylamine binding sites, is able to bind strongly flat organic anions. The crystal structures of the terephthalate 2 and isophthalate 3 inclusion complexes are reported here. Complex 2, triclinic, P-1(N°), a = 7.717(3), b = 10.625(6), c = 16.238(9) Å, = 99.00(7), = 99.70(6), = 109.46(4)°, Z = 1. Complex 3, triclinic, P1 (N°1), a = 7.513(10), b = 10.640(9), c = 16.164(10) Å, = 98.81(5), = 99.77(10), = 109.36(12)°, Z = 1. Comparison of the environment (water molecules, anions and macrocycle) in the two X-ray structures highlights the formation of a similar organized assembly with the two different substrates.     

Synthesis of N-substituted 9-[2-(3,4-methylenedioxyphenyl)-2-oxoethyl]-1,5-dinitro-7,8-benzo-3-azabicyclo[3.3.1]non-7-en-6-ones

Aminomethylation has been accomplished of the anionic Yanovskii adduct of 2,4-dinitronaphthol and 3,4-dimethylenedioxyacetophenone. The structure of the 3-substituted 9-[2-(3,4-methylenedioxyphenyl)-2-oxoethyl]-1,5-dinitro-7,8-benzo-3-azabicylo[3.3.1]non-7-en-6-one was determined by two-dimensional homo-and heteronuclear correlation spectroscopy. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, 1382–1389, September 2007.     

β-Butyrolactone polymerization initiated with tetrabutylammonium carboxylates: A novel approach to biomimetic polyester synthesis

The anionic ring-opening polymerizations of (R,S)-β-butyrolactone and (S)-β-butyrolactone initiated with tetrabutylammonium salts of carboxylic acids as initiators were investigated. Poly[(R,S)-3-hydroxybutyrate] and poly[(R)-3-hydroxybutyrate], with relatively high molecular weights (170,000 and 35,000, respectively) and low molecular weight distributions, were synthesized. Moreover, biomimetic poly(3-hydroxybutyrate)s with well-defined microstructures and predictable iso-dyad contents were obtained. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2184–2189, 2002     

Novel liquid chromatography/mass spectrometry-based approaches for the determination of glyphosate and related compounds: A review

Although glyphosate (Gly) is one of the most widely used agrochemicals, it is also of the most difficult to measure. Gly, its metabolites, and related compounds cannot be sought within the scope of multi-residue methods. Specific so-called single-residue methods are used instead. Liquid chromatography-mass spectrometry (LC-MS) is currently the most widely used technique for determining Gly and its metabolites. This review addresses the different LC-MS-based methods proposed for the determination of Gly and related species in food and environment matrices. Sample preparation (food and environment), as well as their determination based in novel liquid chromatography/mass spectrometry approaches including different specific stationary phases are presented and the specific analytical challenges, strengths and drawbacks are critically discussed.     

ZnCuCoAlNO_3型四元水滑石及其多氧阴离子柱撑物的合成与催化氧化性能

ＺｎＣｕＣｏＡｌＮＯ３型四元水滑石及其多氧阴离子柱撑物的合成与催化氧化性能郭军＊黄兰芳＊＊矫庆泽张斌蒋大振（吉林大学化学系，长春１３００２３）闵恩泽（石油化工科学研究院，北京１０００８３）关键词：ＺｎＣｕＣｏＡｌＮＯ３四元水滑石杂多阴离子柱撑物合成催...     

SDS/CTAB/H2O的双水相性质及萃取作用

正负离子表面活性混合物;牛血清蛋白质;色氨酸;SDS/CTAB/H2O的双水相性质及萃取作用     

Thermal behaviour of synthetic pyroaurite-like anionic clay

Thermal behaviour of synthetic pyroaurite-like anionic clay with molar ratio Mg/Fe=2 was studied in the range of 60-1100°C during heating in air. TG/DTA coupled with evolved gas analysis, emanation thermal analysis (ETA), surface area measurements, XRD, IR and Mössbauer spectroscopy were used. Microstructure changes characterized by ETA were in a good agreement with the results of surface area measurements and other methods. After the thermal decomposition of the pyroaurite-like anionic clay, which took place mainly up to 400°C, a predominantly amorphous mixture of oxides is formed. A gradual crystallization of MgO (periclase) and Fe₂O₃ (maghemite) was observed at 400-700°C by XRD. The MgFe₂O₄ spinel and periclase were detected at 800-1100°C. The spinel formation was also confirmed by Mössbauer spectroscopy.     

Synthesis of a novel block copolymer poly(ethylene oxide)‐block‐poly(4‐vinylpyridine) by combination of anionic ring‐opening and controllable free‐radical polymerization

The block copolymer poly(ethylene oxide)‐b‐poly(4‐vinylpyridine) was synthesized by a combination of living anionic ring‐opening polymerization and a controllable radical mechanism. The poly(ethylene oxide) prepolymer with the 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy end group (PEO_T) was first obtained by anionic ring‐opening polymerization of ethylene oxide with sodium 4‐oxy‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy as the initiator in a homogeneous process. In the polymerization UV and electron spin resonance spectroscopy determined the 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy moiety was left intact. The copolymers were then obtained by radical polymerization of 4‐vinylpyridine in the presence of PEO_T. The polymerization showed a controllable radical mechanism. The desired block copolymers were characterized by gel permeation chromatography, Fourier transform infrared, and NMR spectroscopy in detail. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4404–4409, 2002