ISSN:
0025-116X
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
L-, D-, and various D,L-phenylalanine N-carboxyanhydrides (NCA's) were polymerized with benzylamine and various concentrations of N-methylbenzylamine, respectively, in N,N-diethylformamide at 25°C. Three kinetic stages were observed for all systems: a fast “initiation” stage (I) followed by a slower stage (II) and a faster pseudo-first order propagation stage (III). The initiation rate is higher for N-methylbenzylamine than for benzylamine. The propagation rate constants, kpL, of the stage II polymerization of the L-monomer are independent of initiator type and concentration, whereas the corresponding stage III rate constants vary with the initial monomer/initiator ratio. For each propagation stage, the ratios of rate constants, kpD,L/kpL and kpD,L/kpD, respectively follow the pattern predicted by the absence of crossover reactions. Molar masses calculated from monomer conversion are higher than those determined from amine end group concentration for N-methylbenzylamine initiated polymerizations, but lower for benzylamine initiated ones.
Zusätzliches Material:
7 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/macp.1981.021820603
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