Mechanism of the anionic copolymerization of anhydride-cured epoxies – analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS)

Authors


Abstract

The mechanism of the strictly alternating anionic copolymerization of phenyl glycidyl ether (PGE) and phthalic anhydride (PA) was initiated by various imidazoles. Because of the strictly alternating copolymerization polyesters with a repeating unit of PGE-PA were obtained. The mechanism of the reaction was analyzed by means of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). With this technique the molar masses of the oligomers, the molar mass of the repeating unit, the weight-average molar mass w and the number-average molar mass n, their ratio w/n and the residual molar mass could be calculated. The strictly alternating copolymerization was easy to prove because the molar masses of PGE and PA are slightly different. The question whether the initiator remains chemically bound during the whole reaction could be solved. To this end polyesters obtained by initiation with various imidazoles with different molar masses were synthesized. The calculated residual molar masses correspond exactly to the molar masses of the imidazoles.

Ancillary