Large-amplitude oscillatory shear alignment of a hierarchically ordered system of combshaped supramolecules and the preparation of core-corona nanorods thereof are reported. The supramolecules consist of nearly symmetric polystyrene-b-poly(4-vinylpyridine) diblock copolymers with pentadecylphenol side chains hydrogen bonded to the poly(4-vinylpyridine) blocks. The polystyrene blocks, accounting for approximately 20% (w/w) of the supramolecules, are segregated in hexagonally ordered cylinders inside a matrix formed by the comb-shaped poly(4-vinylpyridine)-based blocks. The matrix further self-organizes in a layered structure below the order-disorder transition temperature of 70 °C. Thus, a cylinder-within-lamellar morphology is formed. Imposing shear leads to considerable alignment of both structures. The cylinders align along the shear flow with the (10) plane parallel with respect to the shear plane. The matrix layers align perpendicular to the cylinders, transverse to the flow. After elimination of pentadecylphenol by dialysis, crew-cut rods of 20-25 nm in diameter and 5-10 µm in length are obtained.

New stereoregular homo-and copolymers with an ester group at every backbone carbon atom were prepared from ethyl, benzyl and tert-butyl diazoacetate (M w of homopolymers up to 690 kDa and copolymers up to 430 kDa). With polarizing optical microscopy we found that the homopolymers poly-(ethyl 2-ylideneacetate) and poly(benzyl 2-ylideneacetate) are able to form stable and accessible thermotropic and lyotropic nematic phases. Both two polymers show relatively high storage moduli up to the glass transition temperature (T g ), as evidenced by dynamic mechanical thermal analysis. The materials retain quite decent storage moduli in a broad elevated temperature range between T g and T m . The formation of (block) copolymers was confirmed by a combination of NMR spectroscopy, differential scanning calorimetry and size-exclusion chromatography. 2D-solubility-gradient chromatography-SEC as well as pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) showed a clear difference in the composition of the random and block copolymers with benzyl and ethyl ester groups. Thermal analysis showed that the homopolymers and block copolymers are semicrystalline, while the random copolymers are completely amorphous. The polymers are thermally stable toward decomposition up to 300 °C (and polymers containing tert-butyl ester groups up to 200 °C). The formation of cross-linked polymer was achieved by heating copolymers containing tert-butyl ester groups.

No abstract

Self-assembled blends of PS-b-P4VP(PDP) supramolecules, obtained by hydrogen bonding of pentadecylphenol (PDP) side chains to poly(4-vinylpyridine), and poly(2,6-dimethyl-1,4-diphenyl oxide) (PPE) were investigated by thermal analysis and small-angle X-ray scattering (SAXS) and compared with blends of PS-b-P4VP and PPE. Differential scanning calorimetry (DSC) measurements showed a single composition dependent T g of the PPE/PS layers for both systems, demonstrating that PPE is distributed throughout the PS layers. Furthermore, DSC showed that for the PPE/PS-b-P4VP(PDP) blends the presence of PDP is not restricted to the P4VP layers. Its partial presence in the PS-containing domains was confirmed by nuclear magnetic resonance (NMR) spectroscopy on PS-P4VP core-corona nanorods prepared from hexagonally self-assembled PS-b-P4VP-(PDP) supramolecules. The results of the SAXS study on the dependence of the lamellar period of PPE/PS-b-P4VP blends on the amount of PPE were in excellent agreement with a theoretical model based on the Alexander-De Gennes approximation assuming a uniform distribution of PPE throughout the PS layers. For PPE/PS-b-P4VP(PDP) blends the dependence of the long period on the amount of PPE turned out to be somewhat stronger, which may be related to the supramolecular comb-shaped nature of the P4VP(PDP) blocks.