Synthesis of imidazole-terminated hyperbranched polymers with POSS-branching points and their pH responsive and coordination properties

An imidazole-terminated hyperbranched polymer with octafunctional POSS branching units denoted as POSS-HYPAM-Im was prepared by the polymerization of excess amounts of tris(2-aminoethyl)amine with the first-generation methyl ester-terminated POSS-core poly(amidoamine)-typed dendrimer, reacting with methyl acrylate, and ester-amide exchange reaction with 3-aminopropylimidazole. The imidazole-terminated hyperbranched poly(amidoamine) denoted as HYPAM-Im was also synthesized with 1-(3-aminopropyl)imidazole from a methyl ester-terminated hyperbranched poly(amidoamine) by the ester-amide exchange reaction. The transmittance of the POSS-HYPAM-Im solution drastically decreased when the solution pH was greater than 8.2. On the other hand, the transmittance of the HYPAM-Im solution gradually decreased when the solution pH at 8.5 and was greater than 9. Spectrophotometric titrations of the hyperbranched polymer aqueous solutions with Cu2+ ions indicated the variation of the coordination modes of POSS-HYPAM-Im from the Cu2+N4 complex to the Cu2+N2O2 complex and the existence of the only one complexation mode of Cu2+N4 between Cu2+ ion and HYPAM-Im with increasing the concentrations. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 26952701