Morphologies of a mixture of polystyrene-block- poly(ethylenepropylene) (PS-PEP) diblock copolymer and polystyrene- block-poly(isoprene-ran-ethylenepropylene) (PS-HPI) were investigated by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Both neat block copolymers had lamellar microdomains. At up to 30mol% content of athylenepropylene units in PS-HPI (denoted as 30 mol% hydrogenation), the mixtures showed two macroscopic phases, i.e. PS-HPI rich and PS-PEP rich phases due to strong segregation between HPI and PEP. At more than 40 mol% bydrogenation, the mixtures formed lamellar microdomains: PS domains and the domains composed of HPI and PEP. In the mixture of PS-PEP and PS-HPI with 40 mol% bydrogenation, localization of PEP chains in the middle of the microphase-separated domains in the direction perpendicular to the interface was observed. However, in the direction parallel to the interface, PEP were aggregated and PS-PEP and PS-HPI with 60 mol% hydrogenation, PEP chains were localized at the center of the microdomains and uniformly distributed parallel to the interface. This variation of the chain distribution were discussed in terms of strength of the interaction between PEP and HPI.
|Number of pages
|American Chemical Society, Polymer Preprints, Division of Polymer Chemistry
|Published - 1996 Aug