Poly N-H-alkylenimine s

In-depth analysis of commercially available B-PEI shows a 1° 2° 3° amine ratio in between 1 1 1 and 1 2 1. Since the primary (1°) amines are derived from (re)initiation, the secondary (2°) from propagation and chain coupling to 1° amines, and the tertiary (3°) from chain coupling to 2° amines, the rate constants of all these reactions must be of approximately the same order, theoretically leading to a 1° 2° 3° amine ratio of 1 2 1. The deviation towards the 1 1 1 ratio can be ascribed to the increase in 

The intrinsic limitation for the direct CROP of IV-H-cyclic amines for preparing defined linear PHAIs is the similar nucleophilicity of the amino groups of the monomer and the polymer. As such, the cationic chain ends are reactive towards both the monomer and the polymer, leading to the formation of hyperbranched polymers. Lower degrees of branching may be achieved by a mixed feed containing both aziridine and an N-suhstituted aziridine, but this also leads to the incorporation of allylated tertiary amine groups.  

The living anionic ring-opening polymerization of NSAz s has been reported by Stewart et al., revealing that the solubility of the formed polymers is very poor. Only the poly(N-sulfonylaziridine)s (PNSAz s) with long all yl substituents on the aziridine rings were soluble in common solvents. 

Although somewhat limited by the chain coupling reactions, the mild deprotection conditions give rise to the possibility of preparing L-PEI block copolymers with other hydrolytically sensitive monomers [such as poly(2-oxazoline)s]. 

Attempts to introduce the simplest N-protecting groups onto aziridine, namely acyl moieties, unintendedly led to the development of the living 

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