Carbazole substituted N -acylated linear polyethylenimines (PEI). synthesis and characterization of poly[ N -(9-carbazolyl)acetylethylenimine] and poly[ N -(2-(9-carbazolyl))propanoylethylenimine]

Abstract

The synthesis of carbazola substituted N -acylated polyethylenimines, namely, poly[ N -(9-carbazolyl)acetylethylenimine] 20 and poly[ N -(2-(9-carbazolyl))propanoylethylenimine] 21 by a grafting reaction onto PEI and isomerization polymerization of the carbazole substituted 2-oxazolines is reported. A complete acylation of amino groups in PEI by the 9-carbazolylacetyl groups was achieved by the p -nitrophenyl active ester method but PEI was only partially N -acylated by the 2-(9-carbazolyl)propanoyl groups under similar reaction conditions. The carbazole substituted 2-oxazolines, namely, 2-(9-carbazolyl)methyl-2-oxazoline 18 and (R,S)-2-[1-(9-carbazolyl)]ethyl-2-oxazoline 19 , were prepared by a base induced cyclization of ß-chloroamides. The ring-opening isomerization polymerization of 18 and 19 in the molten state with a cationic initiator (dimethyl sulfate, methyl triflate, or ethylene glycol ditosylate) gave 20 and 21. Gel permeation chromatography of 20 and 21 obtained with different monomerto-initiator ratios gave evidence of a chain transfer reaction with the monomer. The polymers were characterized by elemental analyses, IR, and 1 H-NMR spectroscopy.