Tailoring of Nanophase Structure in Epoxy/Epoxidized Poly(styrene)-b-poly(isoprene)-b-poly(styrene) Blend by Tuning of the Molar Ratio of Styrene Block

In this work, a good degree of epoxidation on poly(styrene)-b-poly(isoprene)-b-poly(styrene) (SIS) block copolymers containing different styrene content (15, 24, and 43%) has been achieved to get epoxidized SIS (eSIS). Thus, obtained eSIS has been blended with epoxy in different compositions. The role of styrene content on eSIS in generating the nanostructure on epoxy matrix has been carefully studied. The morphological findings have also been confirmed by dynamic mechanical analysis. Compared to other blend systems, a composition of 10 wt % eSIS having 24% styrene content is able to form a highly ordered nanostructure in the epoxy network with highest value of glass transition temperature (T_g). As the ratio of PS block in SIS increased, the plasticization effect due to the penetration of ePI block in the blends becomes less, which reflect in their T_g and thermal expansion coefficient (CTE). 10 wt % of eSIS having 43% styrene content largely reduces the CTE of epoxy matrix.