Glass Transition Behavior of Polystyrene Blocks in the Cores of Collapsed Dry Micelles Tethered by Poly(Dimethylsiloxane) Coronae in a PS-b-PDMS Diblock Copolymer

The micellization of a polystyrene-b-poly(dimethylsiloxane) (PS-b-PDMS) diblock copolymer with the number-average molecular weights (Mn) of 193 000 g/mol for PS block and 39 000 g/mol for PDMS block and the glass transition behavior of the PS blocks in the cores of collapsed dry micelles with PDMS tethered coronae were studied. A range of micelle morphologies was observed by varying the micellization conditions and varying the ratio of the methylene chloride (MC) solvent and the n-dodecane (D) selective nonsolvent. MC is a solvent for both of the blocks, but D is a selective solvent for only the PDMS block. After completely removing the solvents below the glass transition temperature (Tg) of the initially solvated PS blocks in MC via extraction and vacuum-drying, the collapsed dry micelles, which were originally spheres and cylinders, became “tablets” or “ribbons”. The diameters of the “tablets” and widths of the “ribbons” were approximately 50 and 100 nm, respectively. The thicknesses of these textures r...