Polymerisation electrophile du 1,3-pentadiene amorcee par le triflate d'aluminium

Influence of termination and transfer on molecular weight distribution of polymer—10. Chain transfer to monomer and impurity☆

The cationic polymerization of 1,3-pentadiene (PD) initiated by AlCl3 in n-hexane was carried out in the presence of allylic halides, i.e., 3-chloro-1-butene, allyl chloride, and allyl bromide. All these allylic halides strongly hindered crosslinking which is a major side reaction during PD cationic polymerization. Cyclization, another side reaction, was also reduced by the addition of the allylic halides. The influences of these halides on polymer yields and molecular weights are also discussed.

Effect of allylic halides on catiomic polymerization of 1,3-pentadiene

A process for producing a copolymer of an isoolefin and at least one other comonomer comprising the step of polymerizing a reaction mixture comprising an isoolefin, a catalyst and at least one of a cycloconjugated muitiolefin and an unconjugated cyclic olefin in the presence of an activator comprising a carbo cation producing species, a silica cation producing species and mixtures thereof. The process can be practiced using a slurry polymerization approach. One of the main benefits achieved with the present invention is the conversion of the monomers over a shorter period of time and higher percent conversion than when the activator is not used.

Cationic polymerization process and catalyst system therefor

The effects of various allyl chlorides and alkyl halides on the overall yield of polymerization and molecular weight of polyisobutene have been investigated and expressed quantitatively by poison and transfer coefficients. The poison and transfer coefficients of halides have been compared with those obtained previously for corresponding hydorcarbons. The poison coefficients of halides and hydrocarbons can be treated formally in a similar manner (1/Wp vs. [X] plots linear for both classes); however, the appropriate transfer coefficients indicate fundamentally dissimilar transfer mechanisms in these systems (1/MWp vs. [X] plots linear for hydrocarbons, whereas 1/MWp vs. [X]1/2 plots linear for halides). These results are discussed in terms of the allylic termination mechanism.

Contributions to the Mechanism of Isobutene Polymerization. VI. Effect of Halides

The effect of various cyclic and bicyclic olefins on the yield (rate) and molecular weight of polyisobutene has been investigated. Cyclic olefins were found to be both rate poisons and transfer agents and the corresponding coefficients appear to be a function of ring size. Alkyl and aryl substitution on the ring increases both the poison and transfer coefficients. With bicyclic olefins, norbornene and norbornadiene both show moderate and similar poison coefficients, but only the former exhibits transfer activity. These coefficients have been discussed in terms of the allylic termination hypothesis and the known geometry and steric effects of the various rings studied.

S. Bank

Papers

Contributions to the Mechanism of Isobutene Polymerization. VI. Effect of Halides

Contributions to the Mechanism of Isobutene Polymerization. V. Effect of Cyclic Olefins