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Polymerization of 5‐aza‐1‐oxa‐cycloundecan‐4,11‐dione; a mechanistic study
Author(s) -
Robertz Bernd,
Keul Helmut,
Höcker Hartwig
Publication year - 1999
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19990501)200:5<1041::aid-macp1041>3.0.co;2-9
Subject(s) - polymerization , polymer chemistry , chemistry , dimethylformamide , polymer , bulk polymerization , amide , organic chemistry , radical polymerization , solvent
N ‐(3‐Hydroxypropionyl)‐ ε ‐aminocaproic acid lactone [c(3HP‐ ε AC), 1 ] was polymerized in dimethylformamide solution with dibutyldimethoxytin as initiator at 100°C. A strictly alternating poly‐(amide‐ester), poly(3‐hydroxypropionate‐ alt ‐ ε ‐aminocaproate), was obtained, a semicrystalline polymer with a melting point of 145.9°C. The polymerization was found to proceed via a tin alcoholate active species as was deduced from 1 H NMR endgroup analysis of the polymer quenched with water. In addition, the active chain ends were quenched with diphenyl chlorophosphate and analyzed by means of 31 P NMR spectroscopy; a diphenylalkyl phosphate was identified, proving the alcoholate active site. The polymerization follows a pseudo‐first order rate law only at low conversions. However, a linear dependence of the number‐average molecular weight on conversion was found, proving that transfer reactions play a minor part throughout the polymerization process. A mechanism for the initiation and propagation is proposed.