Poly(organophosphazenes) with Oligopeptides as Side Groups: Prospective Biomaterials

Poly(organophosphazenes) with pendent primary amino groups have been synthesized. The sodium salt of 2-(2-aminoethoxy)ethanol, in which the amino group was selectively protected, was allowed to react with poly(dichlorophosphazene). The resulting polymer was amino-deprotected with 80% trifluoroacetic acid to yield the [2-(2-aminoethoxy)ethoxy]phosphazene polymer. The cosubstituent polymer [NP-(OCH₂CF₃) (OCH₂CH₂OCH₂CH₂NH₂)]_n was also synthesized in a similar manner via the sequential treatment of poly(dichlorophosphazene) with sodium trifluoroethoxide and sodium 2-[2-((tert-butoxycarbonyl)amino)-ethoxy]ethoxide. The tripeptides Gly-Pro-Gly and Gly-Val-Ala were assembled at the polymer amino side group termini by step-by-step coupling reactions. The physical and thermal properties of the resultant polymers were examined. Model reactions were also carried out with the use of cyclotriphosphazene small-molecule systems.