Abstract: Bis( β-epoxypropylthioethyl) sulfide(DGEMES) was synthesized from 2,2'-dimercaptoethyl sulfide(MES) and epichlorohydrin and it's structure was characterized by FTIRand MS. Ethylenediamine was used to cure the mixture of DGEMESand DGEBA, a novel optical resins with a high refractive index and low dispersion were obtained. The studies indicated that DGEMESis a good monomer for copolymerization. With increasing it's content, the refractive index and Abbe number of the copolymer can be increased at the same time. The cured resins of DGEMES/DGEBA/ethylenediamine have a higher refractive index 1.59-1.62 and a large Abbe's number 35-39; especially, when the content of DGEMESis 40% in weight, the cured copolymer has a high refractive index(nd>1.60) and a higher impact strength(22.5 kJ/m²), and other well balanced properties, which is also important for optical materials. In addition, B-650 was used as a curing agent, the cured resins of DGEMES/DGEBA/B-650 were prepared, which possess middle degree of refractive index. The n_d and ν_d values of the resins, ranging between 154-156 and 38-40, were measured by refractometer, the optical and mechanical properties of them were discussed in this paper.

Key words: Epoxy resins, Curing agent, Optical resins, Refractive index