Showing papers on "Ionic polymerization published in 1983"

Polymerization inhibitor for vinyl aromatic compounds

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds and a new polymerization inhibitor therefor. The process comprises subjecting a vinyl aromatic compound to distillation conditions in a distillation system and adding to the system the new polymerization inhibitor comprising a mixture of N-nitroso diphenyl amine and a dinitro-O-cresol.

Diaryliodonium salts as thermal initiators of cationic polymerization

Abstract: Diaryliodonium salts (I) undergo efficient thermal decomposition in the presence of copper (II) compounds. Such systems can be employed as a novel class of latent thermal initiators for cationic polymerization. An investigation of the mechanism of the reaction demonstrated that the copper (II) compound is first reduced to the corresponding copper (I) compound, which subsequently reduces the diaryliodonium salt. The cationic polymerization of some typical monomers using these new initiators was carried out to demonstrate the scope of their utility.

Living Polymers and Mechanisms of Anionic Polymerization

Abstract: Following a short introduction and a brief discussion of thermodynamics of propagation, the kinetics and mechanisms of anionic polymerization are reviewed. The systems involving living polymers, a term introduced by this writer, are discussed in greater detail because the existence of various ionic species participating in polymerization was clearly revealed by their studies. Indeed, a large part of this review is concerned with the methods used in identification of these species and determination of their role in various polymerizing systems. The results of such studies are compared with those derived from investigations of radical-anions, carbanions and other ionic species.

Polymers from 1,2-Disubstituted Ethylenic Monomers VI. Monomer-isomerization Radical Polymerization of Diethyl Maleate

Abstract: In contrast to diethyl fumarate (DEF), diethyl maleate (DEM) did not homopolymerize with 2,2′-azobisisobutyronitrile (AIBN), but was found to undergo radical polymerization in the presence of amines such as morpholine (Mor). From the results of radical polymerization of DEF with AIBN and isomerization of DEM with Mor, the radical polymerization of DEM in the presence of both AIBN and Mor is considered to proceed via a new monomer-isomerization radical polymerization mechanism, i.e., DEM is isomerized first to DEF which is then homopolymerized. The most efficient isomerization catalyst was Mor among the amines examined. The apparent activation energies for the monomer-isomerization radical polymerization of DEM was calculated to be 91.9 kJ mol−1 and that for this isomerization was also obtained as 24.7 kJ mol−1. Moreover, Mor also acted as a retarder of radical polymerization of DEF. The composition relation of the copolymer to the feed monomer mixture in the copolymerizations of DEM with styrene, isobutyl vinyl ether, and acrylonitrile in the presence of Mor was found to be similar to that of the respective copolymerizations of DEF.

Mechanism of initiation of the ring-opening polymerization and addition oligomerization of norbornene using unicomponent metathesis catalysts

Abstract: The identities and yields of the low-molecular-weight products formed during ring-opening polymerization of norbornene in benzene solvent using several unicomponent metal halide catalysts (W, Mo, Re, Ru, Os and Ir) were extensively investigated. Dimers and trimers were observed in all cases but were only substantial relative to polymer yields for WCl6 and ReCl5. The rate of formation of the dimers exactly paralleled that of the ring-opened polymer, in marked contrast to the rate of growth of the Friedel–Crafts alkylation product, phenylnorbornene. Cyclo-octa-1,5-diene complexes of Ru, Os and Ir halides were also prepared and found to contain hydride ligands whose concentration seemed to be important in controlling catalytic activity.A general mechanism for both the ring-opening polymerization and the addition oligomerization is developed based on a sequence of steps consisting of reaction of metal hydride with monomer to give the corresponding alkyl-metal complex, which in turn forms a hydridometallacarbene intermediate. While metallacarbenes then propagate ring-opening polymerization, the detailed structures of the dimers and trimers are best explained by a mechanism involving reaction of monomer with the hydridometallacarbene species rather than by the classical alkyl/olefin insertion mechanism for Ziegler–Natta polymerization of alk-l-enes.

Polymerization inhibition process for vinyl aromatic compounds

Abstract: A compound and a process for utilizing the compound to prevent the polymerization of vinyl aromatic compounds, such as styrene, during heating. The composition includes effective amounts of 2,6-dinitro-p-cresol and either a phenylenediamine or 4-tert-butylcatechol respectively, to act as a polymerization co-inhibitor system in the presence of oxygen.

Inverse suspension polymerization process

Abstract: A reverse phase suspension polymerization process conducted using an ionic polymerizable material and a polymerization stabilizer of opposite ionic or potentially ionic charge is modified by including also a water soluble, substantially oil insoluble, ionic non-polymerizable compound having the same charge type as the polymerizable material and having at least one alkyl group containing at least 6 carbon atoms.

Effects and role of the solvents on the plasma-initiated solution polymerization of vinyl monomers.

Abstract: Plasma-initiated solution polymerization of vinyl monomers was carried out in various solvents It was found that the polymerization took place exceedingly rapidly in the presence of water It was also found that radicals generated from the plasma were efficiently trapped by solvated 2,2-diphenyl-1-picrylhydrazyl (DPPH), and from the rate of consumption of DPPH, the rate of radical liberation in the plasma was calculated as about 1×10−5 moll−1 per 1 cm2 of the diffusion area A mechanism for the initiation process was envisioned in terms of the interaction between active species diffused from the gaseous plasma and liquid monomers The possibility of solvation of ionic active species is proposed

Block copolymers of Ziegler-Natta polymerized and anionically polymerized monomers

Abstract: Block copolymers are prepared by using two successive and different catalytic processes, a Ziegler-Natta type polymerization followed by a conventional anionic polymerization.

A Kinetic Study of the Radical Polymerization of Polytetrahydrofuran Macromer

Abstract: The kinetics of the radical polymerization of P-vinylbenzyloxy- and P-vinylphenoxy-polytetrahydrofuran macromers were studied in dilute solutions at 60°C by a spectrophotometric method. In the case of an extremely low macromer concentration ([C=C]<1.6×10−3 mol dm−3), the rate of polymerization was independent of macromer concentration but proportional to the square root of initiator concentration. In addition, the degree of polymerization of recovered polymer was shown by GPC to be about unity in spite of the consumption of nearly all the vinyl groups of the macromer molecules. When the macromer concentration was above 1.6×10−3 mol dm−3, however, the kinetics of the radical polymerization were in accord with those of conventional vinyl monomers. These results are discussed in terms of the low concentration of vinyl groups of the macromer molecules.

Polymers from 1,2-Disubstituted Ethylenic Monomers. V. Radical Polymerization of Dimethyl Maleate in the Presence or Absence of Isomerization Catalyst

Abstract: Although dimethyl maleate (DMM) did not give any homopolymer with a radical initiator, it was polymerized in the presence of some amines via a monomer-isomerization radical polymerization mechanism, i.e., DMM isomerized to dimethyl fumarate (DMF) which then homopolymerized. For this polymerization, some primary or secondary aliphatic amines served as isomerization catalysts, and morpholine showed the most efficient activity. The activation energies for the monomer-isomerization radical polymerization of DMM with di-tert-butyl peroxide in the presence of morpholine and for the isomerization from DMM to DMF with morpholine were 95.9 and 23.0 kJ/mol, respectively. Morpholine was also observed to act as a retarder in radical polymerization of DMF. Moreover, the relationships between rates or copolymer compositions and the feed monomer compositions in the copolymerization of DMM with styrene in the presence of morpholine were found to become close to those of DMF with styrene, although both relationsh...

Process and catalyst for olefin polymerization

Abstract: Solid olefin polymerization catalysts are prepared by forming a solution of an organophosphate or organophosphoramide and certain metal halides and then reacting the solution with a halogenated transition metal compound to form a solid.

Polymerization of isobutene by the inifer technique, 1. Low molecular weight products using 1,4‐bis(1‐chloro‐1‐methylethyl)benzene/BCl3 as initiator

Abstract: The cationic polymerization of isobutene by the “inifer”-technique was studied. Preliminary experiments are described which suggest that useful polymer can be prepared only when BCl3 is rapidly added to the premixed monomer/inifer mixture and that such polymerizations do not go to completion. Some questions regarding the mechanism are discussed and remain open.