摘要:

AbstractThe copolymerization of acrylic monomers (M) [acrolein (AL), methyl acrylate (MA), acrylamide (AM) and acrylonitrile (AN)] with liquid sulfur dioxide (S) at low temperature and high dilution in the presence oftert‐butyl hydroperoxide gives high SO2incorporation into the resulting copolymers. Analysis of the composition of these polysulfones, by elemental analyses and13C NMR, shows that they consist mostly of the MMM, SMM, MMS and MSM triad monomer sequences. Thermal (TG) analyses of selected samples demonstrate that their thermal stability, up to 30% weight loss, increases for different acrylic comonomers as follows: AL

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930901

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA study on the Ce(IV) consumption in the graft copolymerization of methacrylonitrile/n‐alkyl methacrylate mixtures methyl, ethyl and butyl methacrylate/methacrylonitrile (MMA/MAN, EMA/MAN and BMA/MAN) was carried out. Ce(IV) consumption increased with increasing mole fraction of the methacrylate in the monomer feed and with increasing the n‐alkyl group length of the methacrylate, but in no case the consumption was total. The molecular weight distribution of the copolymers was obtained through gel‐permeation chromatography. For all systems investigated, both number‐average molecular weight (Mn) and weight‐average molecular weight (Mw) increased with increasing methacrylate concentration in the monomer feed. The ratiosMw/Mnincreased in the following order: MMA/MAN

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930902

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractAnionic oligomerization of methacrylic esters (methyl (MMA), ethyl (EMA), butyl (n‐BMA),tert‐butyl (t‐BMA) methacrylates) was conducted in a one‐step process by mixing, in tetrahydrofuran, the monomer, an alkali metal (sodium) and a deactivating agent (sulfur ortert‐butyl alcohol). The formation of alcohol due to a nucleophilic attack of the ester group by the methacrylic carbanion was quantified and related to the monomer structure, temperature and nature of the living ends. It was shown that this side reaction is not limited to the propagation step but can occur during the initiation step. From mass spectra and nuclear magnetic resonance (NMR) spectroscopy of the protonated oligomers(tert‐butyl alcohol as deactivating agent), it was concluded that this side reaction led to five‐membered cyclic β‐keto esters during the initiation step of MMA, EMA and n‐BMA monomers only. This implies an intramolecular reaction between one carbanion of the dianionic dimer and the penultimate ester group. It was found that this reaction involves primarily dianionic tail‐to‐tail dimer, even though head‐to‐

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930903

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractAn improved method is described for the preparation of difunctional poly(hexafluoropropylene oxide) of moderate molecular weight (Mn≈ 6000) in good yield (>80 wt.‐%). With the dependence of chain transfer constant on initiator concentration known, at least under controlled conditions, good molecular‐weight control can be ach

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930904

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe synthesis of aromatic poly(amide‐thioether)s by reaction between 4,4′‐thiodianiline, 4,4′‐thiodibenzoic acid and 4‐(4‐aminophenylthio)benzoic acid is studied. Depending on the initial monomer ratio, polymers with head‐to‐head, head‐to‐tail or statistical distribution of amido groups along the polymer chains were obtained. Corresponding triads effects were observed in the1H NMR spectra and assigned. The synthesis of the same aromatic poly(amidethioether)s by reaction between dichlorobenzanilides and Na2S is also studied. Only the Cl substituents in para position to a carbonyl groups are reactive and a head‐to‐head poly(amidethioether) was obtained by reaction ofN,N′‐thiobis(1,4‐phenylene)‐

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930905

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPoly(amide‐thioether)s with different microstructures are studied by13C NMR spectroscopy. Alternating copolymers with head‐to‐head or tail‐to‐head arrangement of amido groups in the chain give quite different NMR spectra which are assigned. The spectra of statistical copolymers exhibit resonances which are not present in the spectra of alternating copolymers due to the existence of new triads. The study of chemical shift differences between the alternating copolymers and copolymers with 4‐iminobenzoyl, terephthaloyl or 1,4‐diiminophenylene units show that these sequencing effects are transmitted through S links but not through CONH links. This was explained by the participation of the sulfur atom in the mesomeric system of the two neighbouring

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930906

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe emulsion copolymerization of styrene with itaconic acid and butyl acrylate with itaconic acid (methylenesuccinic acid), initiated by a redox system in the presence of a nonionic emulsifier, was studied at 40°C. Examination of the influence of itaconic acid on the copolymerization with both monomers showed that the presence of itaconic acid had a negative influence on copolymerization conversion and on the rate of copolymerization. the reaction order with respect to itaconic acid is −0,34 for the copolymerization of itaconic acid with styrene and −1,40 for its copolymerization with butyl acrylate. In the case of the copolymerization with styrene, itaconic acid has no effect on particle number concentration and particle size. Itaconic acid participates in particle nucleation during its copolymerization with butyl acrylate. Formation of oligomeric radicals in the water phase led to a decreasing number of particles and to increasing particle

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930907

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPoly[oxy‐(1,4‐dimethyltetramethylene)oxycarbonyl‐1,4‐phenyleneoxyterephthaloyloxy‐1,4‐phenylenecarbonyl] (1) was synthesized for the first time, and its thermal behaviour was studied by differential scanning calorimetry, thermooptical microscopy, and X‐ray diffraction. The crystal to liquid‐crystal and the mesophase to isotropic transition temperatures are lower by ca. 100°C than the values reported for the unsubstituted polymer. Moreover, the formation of a three‐dimensional order is hindered in the case of the polymer with lateral substituents and can only be achieved by lo

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930908

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe influence of solvents in the suspension polymerization of acrylonitrile and divinylbenzene on the structure of the resulting copolymers was tested. The solvents used were toluene or cyclohexanol in mixtures with aliphatic hydrocarbons. It was found that the solution conditions during the polymerization have no essential influence on both crystallinity and the structure of the dry copolymers. However, the properties of the copolymers differ markedly in the gel state. The copolymers obtained in the presence of good solvents show gel permeabilities and sorbabilities toward phenols several times higher than those of copolymers synthesized in the presence of poor solvents.

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930909

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPolymer‐supported ureas were prepared by copolymerization of the corresponding vinyl monomers and divinylbenzene with 2,2′‐azoisobutyronitrile. These polymers show catalytic activity in the reaction of 1‐bromooctane with solid potassium thiocyanate, although the corresponding monomeric ureas are inactive. The catalytic activity is enhanced remarkably by replacing the amino hydrogen for a methyl group. Further, the catalytic activity is affected by some experimental parameters such as stirring, particle size of the catalyst, degree of crosslinking, and solvent. On the basis of the above results, a plausible catalytic reaction mechanism consiting of collisional contact between the solid catalyst and the reagent is p

ISSN:0025-116X    

DOI:10.1002/macp.1992.021930910

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY