Self-Healing Photocurable Epoxythiol-ene Systems Using an Aromatic Epoxy Resin

Abstract EN

A rapid and efficient method to obtain self-healing epoxy resins is discussed.

This method is based on the use of a thiol-disulfide oligomer obtained by partial oxidation of a multifunctional thiol using a hypervalent iodine (III) compound as oxidant.

The oligomer was characterized by Fourier transform infrared spectroscopy (FTIR), Raman and nuclear magnetic resonance spectroscopies, and gel permeation chromatography (GPC).

The oligomer was a joint component of the thiol-ene system along with a tetra-allyl-functionalized curing agent.

The kinetics of the photopolymerization of diglycidylether of bisphenol A (DGEBA) revealed that conversions of the epoxy groups as high as 80% were achieved in only 15 minutes by increasing the concentration of the thiol-ene system in the formulation.

The disulfide bonds introduced in the copolymer using the thiol-disulfide oligomer allowed the repairing of the test specimens in as little as 10 minutes when the specimens were heated at 80°C or for 500 minutes at room temperature.

The analysis of the mechanical properties using dynamic mechanical analysis (DMA) showed that the specimens displayed a healing efficiency up to 111% compared with the unhealed specimens, depending on the amount of polythioethers present in the copolymer.