Determination of cyclic polyester oligomers by gel permeation chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Polyesters prepared from adipic acid (AA), phthalic anhydride (PA), isophth alic acid (IPA), terephthalic acid (TPA), and 2-butyl-2-ethyl-1,3-propanedi ol (BEPD) were investigated by gel permeation chromatography (GPC) and matr ix-assisted laser desorption/ionization time-of-flight mass spectrometry(MA LDI-TOFMS). All polyesters were found to contain a fraction of low molecula r weight molecules that were identified as cyclic ester oligomers. The most abundant cyclic oligomer varied with the diacid used in the synthesis but, in every case, it was either a dimer or a trimer. In addition, the relativ e amounts of the polyester starting materials influenced the amount of cycl ic oligomers formed in the polyesterification reaction. Copyright (C) 2001 John Wiley & Sons, Ltd.