Mesoporous silica as amine immobiliser for endowing healing functionality to epoxy resin

- Triethylene tetramine hardener was immobilized within the pores of mesoporous silica (SBA 15).
- Epoxy was encapsulated in poly(urea-formaldehyde) microcapsules using dispersion polymerization.
- A combination of immobilized amine and encapsulated epoxy was capable of bestowing self healing functionality to epoxy thermoset.

Feasibility of physical entrapment approach towards the immobilisation of amine hardener in mesoporous silica has been demonstrated for potential applications in the perspective of self-healing. A representative mesoporous silica (SBA-15) was synthesised using polymer-templated technique and employed as a substrate for immobilizing triethylene tetramine, a conventional epoxy hardener. Polymeric composites containing microencapsulated epoxy microcapsules and amine loaded SBA-15 were prepared by room temperature curing. The autocatalytic nature associated with the curing of epoxy remained unaltered due to introduction of either SBA-15 or epoxy loaded microcapsules, as confirmed by calorimetric studies. Healing efficiency, as quantified in terms of the ratio of impact strength before and after healing, was found to increase proportionally with increasing loading of healing additives in the formulation, with complete healing (100%) being exhibited at 20% microcapsule loading.