Static structure factor and chain dimensions in polymer blends with non-local mixing entropy

It is suggested that the non-locality of the entropy part of the interaction parameter in partially miscible blends can be measured directly by scattering experiments. The structure factor computed in the random phase approximation is compared with experiments on weakly crosslinked polystyrene (PS) polyvinylmethylether (PVME) blends. These polymers have significantly different monomer units to form ‘smooth’ (PVME) and ‘rough’ (PS) polymers. An excess scattering is observed and related to the non-locality. It is further shown that these effects are significant near the glass transition of the blend. In particular, the influence of the non-local mixing entropy on the single chain behaviour close to the onset of the microphase separation is studied quantitatively.