Analysis of complex phthalic acid based polyesters by the combination of size exclusion chromatography and matrix-assisted laser desorption/ionization mass spectrometry

• Complex aliphatic polyesters have been prepared in kinetic runs.
• Kinetic samples have been analysed by SEC and the molar mass distributions determined.
• SEC indicates complex composition of the samples.
• Single oligomers were fractionated and analysed by MALDI-TOF, oligomer masses were used to obtain oligomer calibration for SEC.
• Complex functionality type distributions of the kinetic samples and the fractionated oligomers were analysed.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used in conjunction with size exclusion chromatography (SEC) to investigate a model polyester system based on phthalic anhydride–1,2-propylene glycol. The polyesters were synthesized with a 30% molar excess of glycol, with kinetic samples being removed during different intervals of the polyesterification reaction. SEC was used to track the course of the reaction by determining the molecular weight and molecular weight distributions before subsequent off-line coupling with MALDI-TOF MS as a selective detection method to determine the chemical composition, identify the functionality type distributions as well as assist in assigning structural conformations. Mass spectrometry analysis proved to be a highly effective tool to facilitate the identification of the narrowly dispersed fractions obtained from the chromatographic separations as well as serve as a core method to investigate the heterogeneous nature of the bulk kinetic samples. Through the hyphenation of these sophisticated polymer characterization techniques, information on the molecular heterogeneity of the model polyesters, showing a complex variety of possible distributions, was obtained.

Figure optionsDownload as PowerPoint slide