摘要:

AbstractThe series of dinuclear to nonanuclear all‐orthomethylene‐bridged oligophenols 2–9 has been synthesized according to a repetitive reaction sequence involving the C‐orthoregiospecific condensation of appropriate phenoxymagnesium precursors with salicyl alcohol or paraformaldehyde. IR, UV, mass,1H and13C NMR characteristics of these oligomers are discussed. X‐ray crystal structures of 2, 3, and 4 are also

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831101

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe bifunctional initiators, bis(2‐glycylaminophenyl) disulfide (1) and 2, 2′‐azo‐2,2′‐dimethyl‐dipropionohydrazide (2), were used to obtain polymeric initiators of two types: carbon chain initiators with amino end groups initiating the polymerization of amino acidN‐carboxyanhydrides (NCAs) and symmetric polypeptide initiators containing SS or NN groups, which decompose on exposure to UV light or elevated temperature forming free radicals. These polymeric initiators were used to synthesize block copolymers (BC) containing carbon chain and polypeptide blocks ofABAandABstructures. It is shown thatABblock copolymers are capable of aggregation to a much higher extent than those of ABA type. These BC can form liquid‐crystalline polymer structures and undergo control

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831102

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe catalytic effects of three typical metal salts, HgCl2, Hgl2, and ZnCl2, on the ringopening polymerization of (PNCl2)3/(PNCl2)4in terms of the hard/soft concept for acids and bases were studied. The influence of the nature and the concentration of the initiators on the onset of gelation, the extent of polymerization, and on the polymer molecular weight is described. A new technique to follow the substitution reaction of chlorine in poly(dichlorophosphazene) by the 4‐methylphenoxy group is propose

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831103

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractBy use of the quenching technique with14CO and14CO2the number of active centers and the propagation rate constants (kp) were determined for the propylene polymerization on different titanium‐magnesium catalysts in the presence and absence of an organoaluminium cocatalyst. Thekpvalues at 70°C were found to be 500–1000 1·mol−1·s−1, which were confirmed by independent data of molecular mass measurements of the isotatic polymer after a short polymerization time (5 s). Similar isotactic and atactickpvalues were found. The maximum number of active centers for supported titanium‐magnesium catalysts can reach about 10% of the titanium content in the catalyst. Thekpvalues of ethylene polymerization on catalysts active without an organoaluminium cocatalyst were also determined (≈ 104l·mo

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831104

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractPoly(vinyl chloride) of low molecular weight (the fraction extracted with a hexane/acetone mixture (vol.‐ratio 3:2)) was substituted by hydroxyphenyl groups and then analyzed by1H NMR spectroscopy. It was established that the1H NMR spectra of hydroxyphenyl substituted poly(vinyl chloride) prepared by removal of HCl, allows to determine the number of unsaturated end groups and to distinguish between the structures CHClCH2CHCHCH2Cl and CH2CHClCHCHCH2Cl, and even between their trans and cis forms. In addition the1H NMR spectra of hydroxyphenyl substituted poly(vinyl chloride) prepared without removal of HCl allow to determine the total number of u

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831105

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe copolymerization parameters of 2‐acryloyoxybenzoic (AOB) and 2‐methacryloyloxybenzoic (MOB) acids, methyl 2‐methacryloyloxybenzoate (MMOB), andN‐methyl‐N‐phenyl‐2‐aminoethyl methacrylate (MPAM) with styrene in benzene solution were determined and used in the calculation of the Alfrey‐Price copolymerization constantseandQfor AOB, MOB, MMOB, and MPAM. UsingeQthus determined and the corresponding tabulated values for methacrylic acid (MAA), the copolymerization parameters of pairs AOB‐MPAM, MOB‐MPAM, MMOB‐MPAM, and MAA‐MPAM were calculated. They are compared with those determined by the copolymerization of these pairs in which the interaction of functional groups o

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831106

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractMethyl methacrylate was polymerized under UV irradiation (254 nm) at room temperature by hydrogen peroxide in order to give hydroxytelechelic polymers. The polymerization was carried out in the presence of ethanol. An alcohol may be used as a diluent, as a mutual solvent of hydrogen peroxide and the monomer, and as a solvent or nonsolvent of the polymer. The influence of the alcohol is pointed out on the various characteristics of the polymerization; the results are compared with those obtained in methanol.

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831107

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractA series of polysters based on a triad aromatic ester mesogenic unit but containing different poly(alkylene oxide) flexible spacers in the main chain was prepared and its properties examined. The flexible spacers consisted of poly(alkylene oxide)s of varying lengths based on either oligomers of ethylene oxide or propylene oxide. The spacer types, lengths and distributions were found to strongly affect the mesophase and melting behaviors of the polymers. Polymers with spacers having more than 10 units were not liquid crystalline, whereas those of shorter length exhibited mesophase properties. The polymers containing spacers with two, three, or four oxyethylene units showed two mesophases, and the textures of their mesophases suggested that both smectic and nematic phases were formed.

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831108

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractIn contrast to conventional approaches to active centre determination in Ziegler‐Natta polymerization, a method is proposed whereby the active catalyst rather than the polymerization system as a whole is studied. The method is based on the observation that addition of non‐polymerizable olefins such as α‐methylstyrene to catalyst systems promoted with Al(iBu)3leads to displacement of isobutene from the active sites. Active site concentration are derived from quantitative determination of liberated isobutene or labelled cumene derived by quenching the treated catalyst with [O‐3‐H]‐methanol. Values of active site concentration were found to be of the order of 0,3 mmol per mol of V and 2,6 mmol per mol of Ti for VCl3and TiCl3. AA catalysts,

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831109

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe polymerization of 2‐pyrrolidone (1) initiated with its potassium salt (2‐oxo‐1‐pyrrolidinylpotassium) (2) and accelerated by the presence of CO2, was investigated. For the optimal concentration of2(≈5 mol‐%) and 0,5 mol‐% CO2, the most suitable polymerization temperature was found to the range between 45 and 55°C. The variation of CO2concentration, 0,5<[CO2]<3 mol‐%, does not affect the polymerization yield under the optimal conditions. The similarity of the course of polymerization in the presence of CO2directly introduced into the reaction mixture with that in the presence of isolated carboxylate of1, is considered as a proof that CO2is transformed into the active potassium carboxylate of1. The order of polymerization reaction with respect to initiator was found to be ≈0,8 indicating the complexity of the

ISSN:0025-116X    

DOI:10.1002/macp.1982.021831110

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY