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

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 M,,, and the number-average molar mass Mn, their ratio B,,,/Mn 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.

Isoconversional method to explore the mechanism and kinetics of multi-step epoxy cures

“…This alternating anionic copolymerization controls propagation of the polymer chain. The mechanism for this major channel was first proposed by Matejka et al 14) and most recently refined by Leukel et al 15) Trappe et al 16) found that the initiation rate is significantly slower than the rate of propagation. Assuming that the initial stages of epoxy-anhydride cure are controlled by initiation, we may assign the value of L 20 kJ N mol -1 to the activation energy of initiation.…”

From Epoxidized Linseed Oil to Bioresin: An Overall Approach of Epoxy/Anhydride Cross‐Linking

“…The 2MI Lewis base results in the best cured networks of epoxy/fatty diacids, in comparisonw ith 1-methylimidazole, triethylamine, 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU), or dimethylaminopyridine. [37] The acid anhydride/epoxy reactionp rogresses through chain-wise polymerization, [33,34] in comparison to the stepwise mechanism for epoxy/amine cross-linking (Figure 1).…”

“…[34,41,42] Moreover,S teinmann thoroughly investigated the reactiono fe pichlorohydrine, phenyl glycidyl ether (PGE), and DGEBA with am onoanhydride (phthalic anhydride (PSA)) in the presence of various initiators, including modifying the ratio of the initiators. [41] Steinmann showedt hat even purified PSA, recrystallized from toluene, still contained 0.2 mol %o fa cid.…”

MALDI-TOF mass spectrometry in the analysis of synthetic polymers

“…The mechanism of the anionic copolymerization of anhydride-cured epoxides was investigated by Leukel et al [87]. They investigated the strictly alternating copolymerization of phenyl glycidylether and phthalic anhydride, initiated by different imidazoles.…”