Journal of Polymer Science Part A: Polymer Chemistry, Vol.51, No.6, 1359-1371, 2013
Ionic networks derived from the protonation of dendritic amines with carboxylic acid end-functionalized PEGs
The synthesis and characterization of novel ionic networks linked by the ammonium salts of poly(propylene imine) (PPI) dendrimers of the first (PPI G1) and second (PPI G2) generation and two short bis carboxymethyl ether terminated poly(ethylene glycol)s (DiCOOH-PEG) with different molecular weights (Mn approximate to 250 and Mn approximate to 600) are reported. Likewise, an ionic network based on PPI G1 and a long -dicarboxylic acid functionalized PEG (Mn approximate to 4800) were evaluated. Simpler ionic structures based on tris(2-aminoethyl)amine or hexamethylene diamine and the short DiCOOH-PEGs are also investigated. The ionic structures formed were confirmed by differential scanning calorimetry, Fourier Transform Infrared spectroscopy in the attenuated-total-reflection mode, and 1H-13C NMR spectroscopy. A comprehensive 1H NMR analysis revealed that only the primary amines of the PPI G1 dendrimer residing at the periphery take part in the ionic network formation. In the case of PPI G2, the picture is less clear. A thorough investigation of the thermal degradation of the utilized precursors and all the ionic materials prepared was additionally performed by thermogravimetric analysis. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Keywords:carboxylic acid-telechelic PEGs;ionic networks;PPI dendrimers;FT-IR;NMR;glass transition;thermogravimetric analysis (TGA)