Influence of the molecular structure of symmetric block copolymers on the viscoelastic properties of PS/PMMA polymer blends
Friedrich Christian, Jacobs Ulf
Institute of Macromolecular Chemistry & Freiburg Materials Research Center, University Freiburg
Germany

Keywords: compatibilization, interfacial properties, viscoelasticity

---

Usually the morphology of polymer blends is optimized by the addition of appropriate compatibilizers. This process leads to a finer morphology which is accompanied by changes of the interfacial properties of these blends.
On the example of polystyrene(PS)/ polymethylmethacrylate (PMMA) blends with sphere morphology we analyze the influence of different amounts of symmetric block copolymers, P(S - b - MMA), of different molecular weights ranging from 17 kg/mol up to 170 kg/mol on the viscoelastic properties of the blend. We observe significant changes in their properties and we attribute the appearance of the longest relaxation time (longer than the form relaxation time) to the impact of Marangoni stresses. The consideration of these stresses within the Palierne model allows a quantitative correct analysis of the measured relaxation times in dependence on the amount and molecular weight of the block copolymers
Finally, we present first results on the case where the blocks interact enthalpically with the corresponding polymer chains of matrix and dispersed phase. The stability of these polymer blends, i.e. the formation of a sphere in matrix morphology without the formation of micelles, is the crucial point during the handling of these blends.