A near-monodisperse poly(styrene-hydrogenated isoprene) diblock copolymer (28 mol % styrene) prepared via anionic polymerisation forms well-defined polystyrene-core micelles in n-alkanes. The effect of varying the solution temperature on the copolymer micelle structure is studied using transmission electron microscopy, dynamic light scattering, 1H NMR spectroscopy and small angle x-ray scattering. Direct dissolution at 20oC leads to meta-stable worm-like micelles; spherical micelles are formed on heating to 90oC, which are retained on cooling to 20oC. Adsorption of copolymer micelles onto carbon black is also examined. The presence of copolymer at the carbon black surface is confirmed by x-ray photoelectron spectroscopy. An absorption isotherm is constructed using a supernatant depletion assay based on uv spectroscopy to quantify the aromatic chromophore due to the polystyrene block at 262 nm. Evidence is presented for micellar adsorption from n-alkanes and unimer adsorption from chloroform, which is a good solvent for both blocks of the copolymer.

Micellar structure and adsorption behavior of a polystyrene-based block copolymer

245th National Meeting (2013)

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