ISSN:
0449-2951
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Allene has been polymerized to a high molecular weight by several transition metal salts reduced by aluminum triisobutyl. The polymer contained three types of unsaturation: vinylidene, vinyl, and cis; no trans unsaturation was found. A hypothesized mechanism accounted for these facts by two competitive rates: reaction of a linear intermediate with monomer to form again the linear intermediate plus one vinylidene unit, and isomerization of the linear intermediate to a cyclic intermediate which ultimately yielded one vinylidene and one vinyl or cis unit after reaction with monomer. Thus, the ratio of the two rates was controlled by the concentration of allene. The suggested mechanism proved to predict accurately the effect of the conditions of polymerization upon the structures of the resulting polymers. The nature of the transition metal also proved of importance in determining the path of polymerization as did temperature, solvent, degree of agitation, and copolymerization. Polyallene was found to exist in three crystalline forms as well as an amorphous form.
Zusätzliches Material:
4 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1963.100010207
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