Thiol-cured elastomeric epoxy resins

A process for forming a phase-segregated elastomeric polymer, a) forming a reaction mixture containing 1) at least one polyepoxide-terminated polyether having a linear or branched polyether chain that has a molecular weight of at least 2000 and an epoxide equivalent weight of at least 400, which polyepoxide-terminated polyether is formed by the reaction of a polyether that has epoxy-reactive groups and an average molecular weight of 4,000 to 8,000 with an epoxy resin, 2) a curing agent containing at least one polythiol compound having at least two thiol groups and an equivalent weight per thiol group of up to 500, 3) at least one base catalyst and 4) from 10 to 150 parts by weight, per 100 parts by weight of component 1), of an epoxy resin having an average of at least 1.5 epoxide groups per molecule and an epoxy equivalent weight of up to 250 and b) curing the reaction mixture at a temperature up to 60° C. to form the phase-segregated elastomeric polymer that exhibits multiple glass transition temperatures, one of which is −20° C. or lower.