Determination by MALDI-TOF MS of the structures obtained from polytransesterification of diethyl 2,6-pyridinedicarboxylate and poly(ethylene glycol)

Polyesters from reaction of diethyl 2,6-pyridinedicarboxylate with poly(ethylene glycol) 1000 were synthesized through a polytransesterification process using titanium(IV) alkoxide as catalyst. The resulting polyesters were characterized by size-exclusion chromatography (SEC) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). The structures of the polyesters were established and revealed the formation of several cyclic and linear populations of varying size. Detailed analysis of the MALDI-TOF mass spectra of the obtained polyesters has revealed the presence of linear polycondensates bearing various end groups among which those attributed to an exchange reaction between alkyl groups of the catalyst and ester groups of the polycondensates.