ISSN:
0025-116X
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
The absolute rate constants of propagation kp and of termination kt of ethyl α-cyanoacrylate (ECNA) were determined in bulk at 30°C by means of the rotating sector method under conditions to suppress anionic polymerization; kp = 1 622 1 · mol-1 · s-1 and kt = 4,11 · 108 1 · mol-1 · s-1 for the polymerization in the presence of acetic acid, and kp = 1610 1 · mol-1 · s-1 and kt = 4,04 · 108 l · mol-1 · s-1 for the polymerization in the presence of 1,3-propanesultone. The magnitude of kp2/kt determined was 6,39 · 10-3 l · mol-1 · s-1. The absolute rate constants for cross-propagation in ECNA copolymerizations were also evaluated. Quantitative comparison of the rate constants with those of common monomers and polymer radicals shows that the strong electron-withdrawing power of the ethoxycarbonyl and cyano groups enable the poly(ECNA) radical to add to monomers as fast as the other polymer radicals. The relatively high reactivity of ECNA, regardless of the type of attacking polymer radical, is interpreted by a transition state greatly stabilized by both the ethoxycarbonyl and the cyano groups.
Zusätzliches Material:
5 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/macp.1983.021840514
