Dilute Solutions of Diblock Copolymers in a Selective Solvent: I. Evidence for Spherical Star like Micelles

Autor:	M. Adam, Didier Lairez, S. Corona-Vallet, J.-P. Carton
Rok vydání:	1996
Předmět:	Physics and Astronomy (miscellaneous) Chemistry Diffusion General Engineering Theta solvent Analytical chemistry Concentration effect Micelle Atomic and Molecular Physics and Optics chemistry.chemical_compound Polymer chemistry Radius of gyration Copolymer Polystyrene Methylcyclohexane
Zdroj:	Journal de Physique II. 6:1781-1795
ISSN:	1286-4870 1155-4312
DOI:	10.1051/jp2:1996160
Popis:	Diblock copolymer polystyrene-polyisoprene PS-PI is studied in dilute solution at room temperature in methylcyclohexane, a good solvent for polyisoprene and a theta solvent for polystyrene at T θ = 70 °C. The molecular mass of the copolymer is 1.1 x 10 6 g/mol and the polystyrene weight fraction is 36%. The diblock copolymer aggregates into star like micelles which are studied by static and quasielastic light scattering. Both techniques lead to a full characterization of the micelles. Well below the overlap concentration, the data are strongly dependent on micelle interactions. The scattered intensity (the diffusion coefficient) presents a maximum (a minimum) at a scattering vector which is concentration dependent. From this dependence we infer that the micelles are in a liquid phase, the mean distance between first neighbor being 400 nm at a concentration C = 10 -3 g/cm 3 . From these measurements we can deduce the mobility per monomer and demonstrate that the micelles move in an effective medium having the macroscopic viscosity of the solution.
Databáze:	OpenAIRE
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