Applications of ruthenium indenylidene catalysts on ROMP-based self-healing epoxy systems

•Ruthenium indenylidene based metathesis catalysts were used in ROMP-based self-healing systems.•Ruthenium indenylidene catalysts bearing NHC and Schiff base ligands showed high thermal resistance.•Healing efficiencies up to 116% were observed at 120 °C.

In this study, three different ruthenium indenylidene metathesis catalysts (C1-3) were tested as possible catalyst candidates to Grubbs 1st generation catalyst in ROMP based self-healing systems. Bis(tricyclohexylphosphine)-3-phenyl-1H-inden-1-ylideneruthenium(II)dichloride, commercially known as Umicore M1 (C1) and it's N-heterocyclic carbene (NHC) (C2) and Schiff base (C3) substituted analogs were compared as catalyst in means of thermal stability and chemical compatibilities with epoxy matrix and curing agent diethylenetriamine (DETA). Catalysts C1-3 were found to have high thermal resistance. C2 and C3 showed high chemical compatibility with DETA. Self-healing specimens were prepared by mixing dicyclopentadiene (DCPD) containing poly(urea-formaldehyde) microcapsules (10 wt%) and catalysts C1-3 (1 wt. %) with the epoxy resin. All fracture tests were carried out at room temperature using tapered double-cantilever beam geometry (TDCB). The percentage of healing was calculated by comparing the fracture failure load of virgin samples with fracture failure load of healed samples. Healing efficiencies of 23%, 87% and 116% were observed at a healing temperature of 120 °C with a catalytic loading of 1 wt. %.

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