摘要:

AbstractPolymerization of ethylene oxide (EO)‐catalyzed by a binary system consisting of triphenyl‐antimony dibromide (TPAB) and triphenylphosphine (TPP) was carried out. TPAB itself could induce the polymerization, but the addition of TPP to TPAB greatly enhances the catalytic activity. A characteristic inflection point, which appeared clearly in the time‐polymerization curves, divided the polymerization into two successive steps. The preceding process is a cationic step in which an intermediate antimony dialkoxide is produced and the following a coordinated polymerization. The mean consumption of EO per catalyst at the inflection point was calculated to be 45 and was independent of the mole ratio of [TPP]/[TPAB]. It is assumed that TPP coordinates to the central antimony atom to produce an active complex salt in the second step. The effect ofp‐substitution of TPAB in the polymerization was also investigated; the Hammett parameterspfor the first and the second polymerization step were found to be +1,7 and +1,0, respe

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830501

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe copolymerization of methyl acrylate (MA) and isobutylene (IB) in the presence of Lewis acids (EtAlCl2, Et2AlCl, Et3Al, AlCl3, and ZnCl2) at low Lewis acid/MA mole ratio was investigated. EtAlCl2and Et2AlCl were found to initiate the spontaneous reaction. An alternating copolymer was produced in this reaction when an excess of IB in the initial monomer feed was used. The copolymerization in the presence of Et3Al, AlCl3, and ZnCl2did not proceed spontaneously and was initiated by dibenzoyl peroxide (BPO). In this case MA‐rich copolymers are formed even in systems containing a large excess of IB in the monomer feed. The addition of BPO to systems containing ethylaluminium chlorides strongly diminishes the tendency towards alternating propagation. It was concluded that the mode of initiation has a significant influence on the copolymer composition. The alternating copolymerization by EtAlCl2was studied in detail in order to determine the influence of the catalyst concentration, monomer feed ratio, reaction temperature and time on the monomer conversion, copolymer composition, molecular weight and tacticit

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830502

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractN‐Vinylcarbazole (NVC) is polymerised in the presence of pyridine at 60°C by using azodiisobutyronitrile (AIBN) and benzoyl peroxide (Bz2O2) as initiators and the results are compared with those obtained when benzene is used as the solvent. In the AIBN‐initiated system using pyridine as the solvent the rates of polymerisation follow an usual linear relationship with respect to monomer concentration and a square root dependence with respect to the initiator concentration. In the Bz2O2‐initiated system, however, deviations from these ideal behaviours are observed when benzene and pyridine, respectively, are used as the solvent. Initiation occurs through the complexation of the monomer with Bz2O2and degradative transfer is thought to be mainly responsible for this unusual kinetic beh

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830503

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractActive β‐alanine 4‐acyl‐2‐nitrophenyl esters (5a—j) containing ω‐phenyl‐ or ω‐cyclohexyl acyl groups were prepared and their polycondensation was studied, which can take place in the reversed micelle to give poly(β‐alanine). Non‐polar solvents were suitable for the polycondensation, while no polymer was formed in protic and dipolar aprotic solvents. Esters having long linear acyl groups (5n—o) were also reactive enough to give the polymer. However, the esters containing phenyl and cyclohexyl groups (5a—j) were much more reactive and gave the polymer in high yield even if the linea

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830504

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractBy reactingN‐hydroxymethylphthalimide (5a) orN‐chloromethylphthalimide (5b) with an excess of phenol, a mixture of 2‐phthalimidomethylphenol (6) and 4‐phthalimidomethylphenol (7) was obtained. The ratio6/7was found to be 2:3 for the reaction with5aand 3:2 with5b, as determined by1H NMR at 250 MHz. The condensation of6with hexamethyleneteraamine (3) at the mole ratio6/3equal to 2 and 7,5 was performed at 190°C. The resulting resins (HPP) were compared to those prepared fromo‐cresol and3(HOC), and GPC of the resulting products was made. A higher thermal stability of the resins HPP was evidenced by thermogravimetric analysis. This improvement of the thermal stability was also observed for the condensation products of the ortho and para isomers6and7with phenol and formaldehyde, leading to modified novolacs FPP, although the amount of incorporated6and7was found to be less than the original amount in th

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830505

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe thermal and the benzoyl peroxide initiated polymerizations of styrene and methyl methacrylate in presence of three polyconjugated polymers with anthracene repeating units are investigated. Participation in the inhibition reaction of the polymer methylene end groups is shown. A charge transfer complex formation between the polyconjugated polymers as donors and the propagating radicals was assumed as another factor determining inhibition activity.

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830506

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractCopolymers were prepared by reacting a prepolymer consisting of an anhydride terminated polymeric acid from pyromellitic anhydride and a diamine (p‐ orm‐phenylenediamine), with the second diamine. The resulting polymeric acids were converted into polyimides by thermal cyclodehydration. The corresponding random copolyimides were prepared by a conventional procedure and their properties were compared with those of three step copolyimides of similar composit

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830507

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractPolychlorophosphazenes2can easily be obtained by thermal condensation of dichlorophosphinoyliminotrichlorophosphorane (1) under atmospheric pressure at 240–290°C, pure POCl3being eliminated. The different stages of the reaction were studied by chemical analysis,31P NMR, IR spectroscopy, and thin layer chromatography. The procedure enables one to obtain polymers of low and high molecular weights. The samples do not contain any cyclic or reticular polymers. Species of low molecular weights can be separated from those with high molecular weights by treatment with heptane. The total yield of phosphorus is 100% with regard to the starting material. Substitution products (Cl by OCH2CF3) are obtained which are identical with those obtained with the polychlorophosphazenes prepared via classical metho

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830508

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe mechanism of the stereospecific polymerization of 2‐vinylpyridine initiated by organomagnesium compounds in non‐polar solvents, was studied. Triad and pentad data were found to be consistent with a first‐order Markov‐polymerization process.1H and13C NMR studies on model molecules of the active species showed an sp3hybridization of the carbanion and a coordination of the Mg cation by the last and the penultimate pyridine rings of the living chain. The NMR characterization of the monomer coordination with the Mg cation of the active species indicates that two transition states are possible. For steric reasons, only one of them is highly probable, leading to isotactic l

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830509

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractReaction of partially deacetylated chitin with aromatic cyclic carboxylic acid anhydrides such as phthalic anhydride, trimellitic anhydride, and pyromellitic dianhydride was successfully carried out under almost homogeneous conditions in organic aprotic solvents using highly swollen precipitates of water‐soluble chitin with about 50% deacetylation. The resulting amic acid‐chitins were converted into the corresponding imide‐chitins by heating. In addition to imidization, this heat treatment also promotes removal of acid anhydrides reacted at the hydroxyl group giving rise to the formation of selectivelyN‐substituted derivatives. These novel chitin derivatives exhibit a much improved solubility in organic solvents and aqueous alkaline solutions. As anticipated, the imide‐chitins, derived from trimellitic anhydride and pyromellitic dianhydride, showed reactivity toward amine under heterogeneous conditions, and the reaction capacities towardp‐chloroaniline were determined to be 4,2 · 10−4and 4,6 · 10−4mol ·

ISSN:0025-116X    

DOI:10.1002/macp.1982.021830510

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY