ISSN:
0449-296X
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Certain aluminum alkyls and aluminum dialkyl halides in conjunction with suitable simple cocatalysts generating proton or carbonium ion exhibit high polymerization activity and produce high molecular weight polyolefins, diolefins and/or copolymers at comparatively high temperatures. In this paper we report our investigations with AlEt2Cl-Brönsted acid systems used for polymerizing isobutylene and copolymerizing isobutene-isoprene mixtures for high molecular weight products. The cocatalyst is not specific in these reactions. Highly active systems can be obtained with HCl, HBr, CCl3COOH, etc. Evidently proton donors in general (Brönsted acids) may function as cocatalysts in this system. The sequence of polymerization initiation activity of various Brönsted acids in conjunction with AlEt2Cl is HCl, HBr ≫ HF, H2O 〉 CCl3COOH ≫ CH3OH 〉 CH3COCH3. The effect of temperature on the molecular weights was studied. In contrast to linear plots of log molecular weight versus 1/T, obtained for polyisobutylene or isobutylene-isoprene copolymers with conventional Friedel-Crafts halides in the -30 to -100°C range, this Arrhenius plot showed a marked maximum near -70°C for polymers prepared with AlEt2Cl-HCl catalyst systems. Features of this polymerization reaction are discussed.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1968.150061116
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