Synthesis of sugar alcohol-derived water-soluble polyamines by the thiol-ene reaction and their utilization as hardeners of water-soluble bio-based epoxy resins

The allylation reactions of α,α′-diglycerol and d-sorbitol as sugar alcohols, and subsequent thiol-ene reactions with cysteamine hydrochloride produced a new water-soluble tetramine (N4DG) and hexamine (N6SB), respectively. The N4DG and N6SB were used as polyamine-type epoxy hardeners for water-soluble sugar alcohol-based epoxy resins, polyglycerol polyglycidyl ether (PGPE) and sorbitol polyglycidyl ether (SPE). The thermal and mechanical properties of the cured resins (PGPE-N4DG, PGPE-N6SB, SPE-N4DG, SPE-N6SB) were compared with those of the epoxy resins cured with a conventional water-soluble polyetheramine (PEA). Although 5% weight loss temperatures of the epoxy resins cured with N4DG and N6SB were lower than those of the PEA-cured resins, glass transition temperatures, tensile strengths and moduli of the former resins were much higher than those of the latter resins. Especially, SPE-N6SB exhibited the highest Tg (22.8 °C), tensile strength (43.6 MPa) and modulus (990 MPa) among all the cured resins.