Self-healing photo-polymerized thiol-ene networks utilizing bio-based hexaallylated compounds derived from L-cystine and citric acid

[Display omitted] •Thiol-ene photo-polymerized films containing disulfide bonds were prepared.•The cured films were prepared using biobased cystine and citric acid.•A cystine-based film was thrice self-healable at room temperature.•The healing efficiency of the cystine-based film was 99%.•The citric acid-based film with no disulfide bond could not be healed. Bio-based vitrimers have received considerable attention owing to their contributions to carbon neutrality and resource and energy savings. The photopolymerization of hexaallylated compounds (A6CST and A6UDC) derived from L-cystine and citric acid with disulfide-containing polyether dithiol (LP-12) and pentaerythritol-based tetrathiol (S4P) at an allyl:thiol ratio of 1:1 produced thiol-ene network films. Fourier-transform infrared spectroscopy of the cured films revealed that the thiol-ene reaction of the thiol and allyl groups was almost complete. Degrees of swelling of the cured films decreased with an increasing LP-12/S4P ratio. The A6CST- and A6UDC-cured films with higher flexible LP-12 fractions (i.e., higher disulfide contents) exhibited lower glass transition temperatures (Tgs), tensile strengths, and tensile moduli, and could be healed by treatment at a lower temperature and shorter time. The A6CST/S4P cured film was healed by treating at 100 ℃ for 24 h, whereas the A6UDC/S4P cured film without disulfide bond was not healed by the same treatment. The A6CST-based film with the highest LP-12/S4P ratio exhibited the highest healing efficiency (99 %) after treatment at room temperature for 10 h, and self-healed at least three times.