A new self-polymerization took place between acrylic acid (AA) and a mono-aziridine containing compound, e.g. methyl 3-(aziridin-1-yl) propanoate (MAP) upon mixing that resulted in formation of a linear polyethyleneimine (PEI) with amino-ester bonds. This self-polymerization has a key reaction of ring opening reaction occurred between carboxylic acid and aziridine that led to an amino-ester bond formation. The model reactions of trimethylacetic acid (TMAA) with MAP and then with ethyl acrylate (EA) were designed to demonstrat the self-polymerization mechanism. The model reaction product at each stage related to that of polymerization was characterized by FT-IR and FT-NMR. The self-polymerization occurred via three consecutive reactions at ambient temperature, which were acid-base neutralization, aziridine ring-opening and finallyMichael addition reaction. Their average molecular weight of resulting PEI could be over 60,000 in aqueous medium or a higher polymer formation in bulk, which is insoluble in water or any organic solvent. This self-polymerization process could have potential for adhesives, composite materials or other polymer applications.
Journal of the Chinese Chemical Society=中國化學會會誌 57(4)pt.B, pp.901-908