Structural Characterization of Oligomers from the Polycondensation of Citric Acid with Ethylene Glycol and Long-Chain Aliphatic Alcohols

ABSTRACT: The structural characterization of polyestersof citric acid (CA) with ethylene glycol and long-chain ali-phatic alcohols (ROH), prepared by the composition of thereaction mixture being adjusted slightly away from stoichi-ometric equivalence, was performed with 1 H- and 13 C-NMRspectroscopy. The aliphatic alcohols employed were 1-deca-nol, 1-dodecanol, and 1-octadecanol. The 13 C-NMR carbonylregion presented four groups of signals, two correspondingto the ester groups and two corresponding to the acidgroups. However, symmetric and asymmetric groups of CAmoieties were identified in the 13 C-NMR spectra. The esteryield from ROH decreased as the number of carbon atoms inthe alcohols increased. © 2003 Wiley Periodicals, Inc. J ApplPolym Sci 88: 302–306, 2003 Key words: polyesters; NMR; colloids; step-growth poly-merization INTRODUCTION Polyesters of citric acid (CA), which form insolublecrosslinked networks, have been used as polymericmatrices for controlled and sustained drug release