Orientation of supramolecular self-organized polymeric nanostructures by oscillatory shear flow

Macroscopic orientation of self-organized supramolecular polymeric material s has been demonstrated by oscillatory shear flow using in-situ small-angle X-ray scattering (SAXS). In the case when a homopolymer poly(4-vinylpyridi ne) and pentadecylphenol molecules are stoichiometrically complexed to form comb copolymer-like supermolecules, the self-organized lamellar local stru ctures align parallel when sheared below the order-disorder transition temp erature at 56 degrees C using 0.5 Hz frequency and 100% strain amplitude. T herefore, the hydrogen bonds between the phenolic and pyridine groups are s trong enough to withstand the applied flow. In the case of a diblock copoly mer of polystyrene and poly(4-vinylpyridine) stoichiometrically complexed w ith pentadecylphenol molecules to form the supermolecules, the self-organiz ation yields lamellar-within-lamellar local structure near room temperature . The larger lamellar diblock copolymer structure showed a parallel orienta tion relative to the shearing plates upon shearing at 125 degrees C (i.e., above the order-disorder transition of the short length scale comb copolyme r-like structure) with initially 0.5 Hz and finally 1 Hz, both at 50% strai n amplitude. On cooling, the short length scale lamellar structure, consist ing of poly(4-vinylpyridine) block and pentadecylphenol, is formed inside t he layers of the comb copolymer-like material in perpendicular orientation.