SANS Study of Ring Topology Effects on the Miscibility of Polymer Blends

Highly purified hydrogenous ring poly­(4-trimethylsilylstyrene) (h-PT) and deuterated ring polyisoprene (d-PI) samples as well as their linear counterparts were prepared, and the miscibility of three kinds of polymer blends, i.e., linear–linear, ring–linear, and ring–ring, denoted as L–L, R–L, and R–R, respectively, with all 50/50 vol % was evaluated by small angle neutron scattering (SANS) measurements. PT and PI are known as a miscible polymer pair with lower critical solution temperature (LCST) type phase diagram. At low-q regime of the scattering profiles, R–R blend exhibits much higher scattering intensity than L–L and R–L, while the latter two show similar profiles. Moreover, from Zimm’s analysis, the spinodal temperature of R–R was estimated to be about 100 °C lower than the other two blends, L–L and R–L. These results suggest that the miscibility of R–R is considerably lower than the other two blends, which is a clear manifestation of the topological effect on the phase behavior of the present blend.