Thermische Aktivierung von Vitrimeren durch thermisch-latente Katalysatoren

Translated title of the contribution: Activation of vitrimers using thermally-latent catalysts

Matthias Udo Kriehuber

Research output: ThesisMaster's Thesis

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Abstract

The research on chemically induced self-healing materials has gained increased attention over the past years, due to the environmentally friendly possibilities of waste reduction and enhanced longevity of future polymer-based products. Vitrimers are prominent intrinsically healable polymers, which are capable of undergoing thermo-activated dynamic associative exchange reactions. Above the topology freezing transition temperature (TV), the exchange reactions become significantly rapid, and the polymeric material has the ability to flow comparable to a viscoelastic liquid, although it is still in a crosslinked state. Vitrimers relying on dynamic hydroxyl ester links, require the addition of a transesterification catalyst to facilitate fast bond exchange reactions above TV. In the current study, selected thermo-base generators (TBGs) were synthesized as a new generation of transersterfication catalysts. A series of quaternary ammonium salts (QAS) were prepared, and the thermally triggered release of the base was studied in detail by employing thermogravimetric-analysis (TGA), evolvedgas-analysis (EGA), NMR spectroscopy and basicity tests. The salt formation proceeded in the presence of carboxylates from weak carboxylic acids. After the surpassing of a specific activation temperature of the TBG (TTBG) and an activation time (tTBG), the decarboxylation of the carboxylic acid takes place. Due to this thermally induced decomposition, the acid forms cleavage products and cannot further stabilize the base, which triggers a base release and an accompanied rise in basicity. Due to this increase, rapid transesterification at temperatures above TV can be observed. The synthesized TBGs were incorporated in selected networks such as thiol-epoxy and thiol-ene. The network properties were studied prior to a and after the thermally controlled release of the base Stress relaxation experiments revealed that exchange reactions are efficiently activated by the thermal release of the basetesting. Due to their enhanced longevity, there is a broad field of applications (e.g., automotive, train or aircraft industry) for future polymer-based products, which would benefit from the abilities of the self-healing material properties of these thermally activated vitrimers.
Translated title of the contributionActivation of vitrimers using thermally-latent catalysts
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Schlögl, Sandra, Supervisor (internal)
Award date16 Dec 2022
Publication statusPublished - 2022

Bibliographical note

no embargo

Keywords

  • vitrimers
  • thermally-latent catalysts
  • transesterification catalyst
  • thermo base generators
  • TBG

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