摘要:

AbstractPolyureas and polythioureas were prepared under mild conditions by direct polycondensation of carbon dioxide and carbon disulfide, respectively, with diamines in the presence of diethylN‐acetyl‐N‐methylphosphoramidite or its analogs containing an active PN bond. The influence of the substituents in the phosphoramidite, of the CO2pressure, solvent, organic base and diamine structure on the yield and inherent viscosity of the polymer was investigated. A reaction mechanism involving the intermediate formation of a mixed anhydride of dialkylphosphorous and alkyl(aryl)carbamic acid is di

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891101

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

Abstract1‐Phenylethylpotassium (5), an efficient anionic polymerization initiator in tetrahydrofuran (THF) solution serving as a substitute for 1‐methyl‐1‐phenylethylpotassium in most of its applications, was obtained by cleavage of bis(1‐phenylethyl) ether (1) with potassium. Ether cleavage reactions were carried out in THF at mole ratios potassium/1= 2/1 and 1/1, and the resulting solutions were submitted to careful analysis. All by‐products formed in the reaction media were unambiguously identified and their mole fractions in the resulting mixture determined. The presence of these by‐products was found not to influence the initiat

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891102

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

Abstract(18‐Crown‐6)‐bridged phthalocyanine network polymers4–8as well as a low‐molecular‐weight model compounds with only one phthalocyanine unit (3a, b) were prepared from tetracyanodibenzo‐18‐crown‐6 (2a). The cyano end groups were partially converted into imido groups during the cyclotetramerization reaction, as detected from the IR spectra. In order to obtain structurally uniform compounds with the same end groups, the C  N groups were hydrolyzed into imido groups with conc. sulfuric acid. The metal‐free phthalocyanine polymer4awas obtained by the reaction of2aeither with hydroquinone or PbO in ethylene glycol. The chlorides of Cu(II), Ni(II), and Co(II) were empolyed in order to synthesize the corresponding metal‐phthalocyanine polymer, and Fe(CO)5was used for the preparation of the Fe‐analog7a. For the preparation of the Co‐containing polymer8aammonium molybdate has to be added as catalyst. The selectivity of7afor Rb+was found to be highest in the heterogeneous phase extraction experiments. Polymers4–8are also capable of binding silver from a

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891103

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe redox catalyzed addition of compounds such as Cl3CCF2CCl3and Cl3CCF2CCl2CH2CHClCH2OCOCH3to allyl acetate was studied with the purpose of obtaining telechelic products. RuCl2[P(C6H5)3]3was used as catalyst, and its action was compared to that of cooper‐ or iron‐based catalysts. The products were isolated and their structures studied by means of13C,19F and1H NMR spectroscopy. The reaction mechanism was studied to improve the yield of the diaddition product for its utilisation as monomer in polycondensation reactions. It was found that the low reactivity for a second addition is not due to the presence of a chlorine atom in β‐position of the acetate function. When allyl acetate was replaced by allyl bromide or chloride in the first addition, the second addition to allyl ace

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891104

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractSix different linear polyesters based on phthalic anhydride, maleic anhydride, 1,4,5,6,7,7‐hexachlorobicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboxylic acid (HET‐acid) and 1,2‐propanediol were synthesized. The polyesters were pyrolysed by heating dynamically at a rate of 10 K · min−1from 40 to 440°C. Apart from the dynamic pyrolysis, the standard unsaturated polyester was isothermally pyrolysed at five different temperatures (200, 250, 300, 350 and 400°C) for 60 min. The pyrolysis products obtained were separated in a capillary gas chromatograph and identified using a mass‐selective detector. In all the polyesters investigated, the corresponding anhydride was formed in major quantities. A variety of low‐molecular‐weight compounds such as propanoi isomers, isomeric dimethyldioxanes, 1,2‐propanediol, 5‐hydroxy‐2‐pyrone and its 6‐alkyl substituted derivatives, polychlorocyclopentadienes and considerable quantities of complex mono‐ and diesters of the diacid component were identified. The presence of HET‐acid units in the polyester chain alters the course of the degradation of the diol units considerably by suppressing the formation of 1,2‐propanediol and increasing the formation of isomeric dimethyl‐dioxanes, 1‐propanol and 2‐propanol. In the thermal degradation of HET‐acid containing polyesters, the formation of HET‐anhydride is favoured in comparison to the retro‐Diels‐Alder reaction in chain. The mode of formation of the products identified by gas chromatography/mass spectrometry analysis is discussed in th

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891105

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractSmall‐angle X‐ray scattering (SAXS) analysis using MoKαradiation is successfully applied to a determination of the crystallite sizes of TiCl3catalysts. The sizes of TiCl3catalysts dispersed in nascent polypropylenes differing in polymer yield are determined by using this technique. It is shown that the original catalyst size does not change during the course of polymerization. This result agrees with the observation by transmission electron microscopy (

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891106

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractWith a new type of high‐pressure cell the angular dependence of light scattering intensities at scattering angles θ between 30° and 150° can be measured as a function of pressureP.The linear extrapolation of (Iθcorr)−1as a function of sin2(θ/2) to θ = 0 does not show an angular dependence of the scattering intensities. For this result the term including sin2(θ/2) in Debye's equation for the critical opalescence vanishes. The reason for this is probably due to the low molar mass of the polystyrene (number‐average molar massM̄n= 1 000 g/mol). This means that the range of molecular forces of a polymer/solvent system is too small to be detected by light scattering. A second linear extrapolation of (Iθcorr)−1to θ = 0 as a function ofPyields the spinodal points of the system polystyrene/pentane in the temperature‐pressure‐

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891107

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe polarized fluorescence spectra and the time‐resolved fluorescence decay of some novel carbazole‐containing polysiloxanes were measured in solution and in the solid state. The fluorescence data show that these polymers, due to the conformational freedom of the carbazole group, are free of excimer‐forming sites. As indicated by the extensive fluorescence depolarization in solid solution, the migration of excitation energy along the chain is fast with respect to the fluorescence lifetime, and the number of migrational steps comes up to the number of chromophores per chain. If the polymers were prepared starting from commercial carbazole (which contained small amounts of aromatic impurities), the occurrence of sensibilized benzocarbazole‐like fluorescence in the solid state and in concentrated solution demonstrates the high efficiency of transferring the excitation energy to a suitable a

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891108

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractReaction of hexachlorocyclotriphosphazene (syst. name: 2,2,4,4,6,6‐hexachloro‐1,3,5,2λ5,4λ5,6λ5‐triazatriphosphorine) (1) with 4‐hydroxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl(2a)gave the hexa‐substituted λ5‐cyclotriphosphazene3a.Electron paramagnetic resonance spectra at low concentrations (10−5mol/L) showed a singlet only (no triplet) due to spin‐spin exchange in the molecule. The paramagnetic molar susceptibility amounts to 7229 · 10−6cm3/mol at 300 K and does not depend on the magnetic field strength.3aobeyed the Curie‐Weiss law between 36 and 296 K demonstrating that there is no

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891109

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractHighly orientedtrans‐polyacetylene prepared by the method of Edwards and Feast was reduced by exposure to various potassiumorganic compounds. The degree of reductionycould be adjusted to values betweeny= 0,01 andy= 0,15. X‐ray investigations performed with samples held under in situ conditions revealed 3 different structures. Long‐range order could not be observed up toy= 0,10. For 0,11 ≤y≤ 0,15 the chains pack in a square lattice. Here and fory≤ 0,10 the chains are not in register. The distance between K+ions which are arranged in chains of various lengths is controlled by thetrans‐polyacetylene (0,48nm). Threedimensional order is only observed fory= 0,15, the chains, however, are then tilted with respect to a square basal plane, and K+ions are only

ISSN:0025-116X    

DOI:10.1002/macp.1988.021891110

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY