ISSN:
0022-3832
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
The usual occurrence of structural units of vinyl polymers in head-to-tail sequence is attributed to the stabilization of the free radical of the growing polymer chain by the monomer substituent(s). Addition at the unsubstituted carbon of the vinyl group reproduces a free radical of lower energy than does addition at the substituted carbon. In at least one instance (vinyl acetate polymerization) a very small percentage of head-to-head addition takes place in spite of this energy difference. These ideas can be extended to polymers of dienes. Here the problem is complicated by the simultaneous occurrence of 1,2 (or 3,4) as well as 1,4 addition. In the case of an unsymmetrical diene monomer such as isoprene it is possible, from detailed examination of the structure of the polymer, to distinguish between preferred addition at carbon atoms 1 and 4 of the monomer.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1947.120020106
