Thiol-En basierte Vitrimere für Formgedächtnis-unterstützte Selbstheilung von Photopolymeren

Translated title of the contribution: Thiol-ene based vitrimers for shape memory assisted self-healing of photopolymers

Tiago Hron

Research output: ThesisMaster's Thesis

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Abstract

Vitrimers are an emerging material class that combines properties of thermosets and thermoplastic polymers. They are covalently cross-linked and therefore have good mechanical properties and high chemical resistance under ambient temperatures. At higher temperatures, the covalent network is adaptable due to chemical exchange reactions and the material can change its topology like thermoplastics. Possible applications are self-healing, shape memory and recycling. For this work, a vitrimer based on a thiol-ene photopolymer was developed and characterized. Subsequently, its applicability for shape memory-assisted self-healing was studied. Dynamic mechanical analysis showed a linear correlation between the thiol content and the glass transition temperature (Tg) of the related photopolymers. The Tg of the formulations amounted to 30°C for a formulation with 14 mol% thiol and 58 °C at 3.5 mol%. Thermal gravimetric analysis proved the high thermal stability (up to 203 °C) of the network and stress relaxation kinetics confirmed the vitrimeric nature of the network. Reaction kinetics revealed high conversion rates for both acrylate monomers and thiol cross-linkers and curing was accomplished within seconds. Specimens were produced, stretched under elevated temperature (above the network’s Tg) and scratched. At high temperatures, the scratch closed due to shape recovery and chemical healing was obtained due to thermo-activated bond exchange reactions. Scratch closure was investigated under the microscope. The lower the thiol content and the larger the scratch size the more self-healing is hindered. However, by using an optimized network composition, tensile testing showed that damaged and healed specimens had nearly the same tensile strength and ultimate elongation as their undamaged counterparts. The healed scratch was not a weak spot anymore and the samples were breaking cohesively at other parts of the test specimen.
Translated title of the contributionThiol-ene based vitrimers for shape memory assisted self-healing of photopolymers
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Schlögl, Sandra, Supervisor (internal)
Award date25 Jun 2021
Publication statusPublished - 2021

Bibliographical note

embargoed until null

Keywords

  • vitrimers
  • shape memory
  • self-healing
  • photopolymers

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