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Synthesis and characterization of poly‐ L ‐lysine with controlled low molecular weight
Author(s) -
Van DijkWolthuis Wendelmoed N. E.,
van de Water Leon,
van de Wetering Petra,
Van Steenbergen Mies J.,
Kettenesvan den Bosch Jantien J.,
Schuyl Wijnand J. W.,
Hennink Wim E.
Publication year - 1997
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/macp.1997.021981211
Subject(s) - diethylamine , triethylamine , polymer chemistry , chemistry , polymerization , monomer , end group , polymer , lysine , organic chemistry , amino acid , biochemistry
N ‐Carboxy‐( N ϵ ‐benzyloxycarbonyl)‐ L ‐lysine anhydride (Z‐ L ‐lysine NCA) was polymerized in dimethylformamide with triethylamine, diethylamine or hexylamine as initiator, at varying molar ratios of NCA to initiator (M/I ratio). After removal of the protecting Z‐group the resulting poly‐ L ‐lysine was characterized with 1 H NMR and MALDI TOF MS. Both diethylamine‐ and hexylamine‐initiated polymerization yielded poly‐ L ‐lysine in which the initiators were incorporated at the carboxylic end of the polymer. This indicates that the NCA polymerization occurred exclusively via nucleophilic attack of the initiator on the monomer. On the other, hand, when triethylamine was used as the initiator, poly‐ L ‐lysine was obtained in which no triethylamine‐derived end group could be detected by MS. These polymer chains are most likely end‐capped with an N ‐acyl‐2,5‐dioxopiperazine group at the carboxylic end of the polymer. Incorporation of diethylamine and hexylamine allowed determination of the degree of polymerization (DP) of the obtained polymers by 1 H NMR. The DP depended linearly on the M/I ratio, for both diethylamine and hexylamine, with higher DPs for the diethylamine‐initiated poly‐ L ‐lysine at equal M/I ratio.