摘要:

The alternating copolymerization of butadiene and an acrylic compound in the presence of ethyl aluminum dichloride and vanadium oxychloride as complexing agents was studied kinetically for the comparison of two mechanisms, i. e., one involving an intermediate of a ternary complex of butadieneacrylic monomer-EtAIClz and the other without the complex formation. The rate of propagation was found to attain a maximum at a definite monomer composition, and this composition is not varied by changing the amount of EtAICl2but decreased with increasing the concentration of total monomer. This fact is explained only by the mechanism of the ternary complex intermediate. In relation to the mechanism, NMR study of the ternary complex, ESR study of the growing radical NMR study of the regularity of the copolymer, and the elementary reaction of the propagation are reviewed with discuss ion.

ISSN:0022-233X    

DOI:10.1080/00222337508081497

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The equimolar alternating copolymerization of methyl methacrylate (MMA) with styrene (St) in the presence of stannic chloride in toluene (Tl) is investigated kinetically. The concentrations of the ternary molecular complexes, [SnCl4-MMA … St] and [SnCl4-MMA … T1], are calculated by use of the formation constants of the ternary molecular complexes. The rates of copolymerization under photo-irradiation and with tri-n-butyl boron-benzoyl peroxide as an initiator are proportional to the 1.5th order and 1. Oth order, respectively, of the concentration of the ternary molecular complex [SnCl4· MMA … St]. The alternating copolymerization precedes the homopolymerization of the methyl methacrylate charged in excess. The alternating regulation of the copolymerization is ascribed to the homopolymerization of the ternary molecular complex from the kinetic results. The magnitudes of the shifts for

ISSN:0022-233X    

DOI:10.1080/00222337508081498

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

New examples for the monomer-isomerization polymerizations of some branched internal olefins, 4-methyl-2-pentene and 4-phenyl-2-butene, are presented. When these olefins are polymerized with A1(C2H5)3-TiCl3([TiCl3] = 120 mmole/liter, A1/Ti = 3.0) catalyst at 80°C, considerable amounts of high polymers [27.5%/60 hr ([η] = 0.68 d1/g) and 35.6%/100hr, respectively] were obtained. From the additional fact that the isomerization from these 2-olefins to the mixture of their positional isomers including 1-olefins was observed during the polymerization, it is assumed that the polymerizations from these 2-olefins are performed with the 1-olefins which isomerized from the starting 2-olefins.

ISSN:0022-233X    

DOI:10.1080/00222337508081499

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

When certain catalysts that display a low apparent metathesis activity on terminal olefins are employed on mixtures of terminal and internal olefins, they lead to a selective formation of cross metathesis products. Critical experimentation using deuterated 1-pentene reveals that terminal olefins prefer to scramble “head-to-tail”. A study of the macrocyclics distribution produced at various conversions during 1,5-cycloocta-diene polymerization suggests that these are being formed exclusively via an intramolecular transalkylidenation. The significance of the two sets of results is discussed in terms of two basic mechanistic schemes.

ISSN:0022-233X    

DOI:10.1080/00222337508081500

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Transition metal alkyls and hydrides isolated from Ziegler-type catalyst mixtures serve as appropriate models for coordination polymerization. These transition metal complexes initiate the polymerization of some vinyl compounds and aldehydes. In some cases the monomer-coordinated complexes may be isolated and the interaction of the monomer with the transition metal complexes may be studied. Comparison of the polymerization kinetics of the vinyl compounds with the decay kinetics of the initial transition metal complexes on interaction with the monomer provided important information with respect to the mechanism of coordination polymerization by these complexes. The effect of organoaluminum compounds on the reactivity of the transition metal complexes has been also studied. These transition metal alkyls initiate the polymerization of acetaldehyde to give a polyether-type polymer at -78°C and a polymer with OH groups at room temperature.

ISSN:0022-233X    

DOI:10.1080/00222337508081501

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Alkyl α-chloroacrylates and p-substituted α-methylstyrenes were investigated for the effect of polymerization conditions on tacticity, molecular weight, and distribution, and for the relationship between tacticity, glass temperature, and crystalline properties.

ISSN:0022-233X    

DOI:10.1080/00222337508081502

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Polymerization activities of the soluble Ziegler-type of catalyst systems, Ti(OR)4-AlEt3, Ti(NEt2)4-AlMe3, and V(NEt2)4-AlEt3, were investigated. In the catalyst system of Ti(OR)4-AlEt3, formation of two types of Ti(III) compounds, i.e., Ti(OR)2Et and its bridged complex with aluminum alkyl, was confirmed by IR and ESR measurements. With the addition of donor molecule to the system, it was found that the polymer yield decreased remarkably and that the bridged complex dissociated into a single or uncomplex Ti(III) paramagnetic species. It has been concluded that the bridged structure of Ti(III) species was responsible for the polymerization activity of styrene. Two reaction products of Ti(NEt2)3Me and Al(NEt2)Me2were found by NMR spectroscopic observation with the Ti(NEt2)4-AlMe3catalyst system. From the kinetic study of polymerization of styrene, it was found that Ti(NEt2)3Me is an active species. An anionic mechanism was proposed for the styrene polymerization by Ti(NEt2)3Me. In the polymerization of MMA with the V(NEt2)4-AlEt3system, a difference in the tacticity of polymer was found to depend on the polymerization conditions, e.g., AI/V ratio and temperature. From an analysis of the tacticity of the polymer, the presence of two active sites in the propagation process is suggested.

ISSN:0022-233X    

DOI:10.1080/00222337508081503

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The anionic polymerizations and copolymerizations of methacrylates were investigated. The studies were focused on the stereoregularity of the polymers and the relative reactivity of the monomers in relation to the stereospecificity of polymerization.

ISSN:0022-233X    

DOI:10.1080/00222337508081504

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Initiation of the polymerization of dienes bearing allylic protons with metallic alkali metals were investigated. Addition of a tertiary amine into the solution resulted in the complete inhibition of the polymerization to give a mono- or dianionic dienylmetal compound and reduced dimers in quantitative yield. The planar conformations of the isolated dienyl alkali metal compounds, which are considered to be real active species toward the alkali-metal catalyzed polymerizations, were determined by PMR and13C NMR spectroscopy. The catalytic activity toward polymerization as well as the chemical reactivity of those dienyl alkali metals was investigated.

ISSN:0022-233X    

DOI:10.1080/00222337508081505

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The ionic polymerization of vinyl monomers possessing aromatic and heterocyclic functional groups has not been studied in any systematic fashion. Only in a few isolated cases have detailed mechanistic and structural studies been reported. The anionic polymerization of a number of vinylanthracene monomers has recently been investigated and some rationalization of this system is presented. The cationic and anionic polymerization of the N-, 3-, and 2-vinylcarbazole series of monomers is discussed in some detail. The important role of vinyl aromatic/vinyl heterocyclic monomers, i.e., diphenylethylene and the vinylcarbazoles, in elucidating the mechanistic aspects of cationic polymerization, “change transfer” polymerization, and photoionic polymerization is considered.

ISSN:0022-233X    

DOI:10.1080/00222337508081506

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor