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.

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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.

Para-substituted alkyl and alkoxy phenylazophenols (PAP's) have been synthesized and used as hydrogen-bonded side chains for poly(4-vinylpyridine)-based comb-shaped supramolecules akin to the wellstudied poly(4-vinylpyridine)/pentadecylphenol systems. In this paper we report the self-assembly of these new materials as investigated by DSC and simultaneous SAXS/WAXS. The systems exhibit smectic ordering with a periodicity in the range of 3.0-4.2 nm. The periodicity length scale, the order-disorder transition temperature (T ODT ), and the glass transition temperature T g of the self-assembled systems all increase with increasing alkyl chain length. The correlation between T ODT and T g observed is argued to be the consequence of the increasing segregation in the self-assembled systems with increasing alkyl tail length of the amphiphiles.

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Citation for published version (APA): Polushkin, E., Bondzic, S., de Wit, J., van Ekenstein, GA., Dolbnya, N. V., Bras, W., ... Ikkala, I. (2005). Insitu SAXS study on the alignment of ordered systems of comb-shaped supramolecules: A shear-induced cylinder-to-cylinder transition. Macromolecules, 38(5), 1804-1813. https://doi.org/10.1021/ma048314k Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. ABSTRACT: A tooth rheometer, designed to investigate in-situ the influence of large-amplitude oscillatory shear on the macroscopic orientation of complex fluids, is used to study the alignment of two supramolecular systems composed of a polyisoprene-block-poly(2-vinylpyridine) block copolymer with octyl gallate (OG) hydrogen bonded to the vinylpyridine block. The molecular ratio x between OG and pyridine groups in these two PI-b-P2VP(OG) x systems is 0.50 and 0.75, respectively. In both cases, a hexagonally ordered cylindrical self-assembly was revealed by small-angle X-ray scattering in a broad temperature range. The spacing of the hexagonal structure decreases significantly on heating and reversibly increases on cooling. In in-situ SAXS experiments, performed with the tooth rheometer, a gradual macroscopic alignment of the nanoscale structure is observed on heating for both supramolecular systems. The most striking feature is a shear-induced transition from one hexagonal structure to another, more aligned, hexagonal structure observed for PI-b-P2VP(OG) 0.75 in the temperature range 120-140°C. The transition is accompanied by an abrupt reduction of the domain spacing and additionally by a decrease of the phase angle measured by the rheometer. In the PI-b-P2VP(OG) 0.5 system a comparable reduction in the spacing is observed at 90-95°C. In this case, it coincides with the most intensive macroscopic alignment of the sample, proceeding in a continuous rather than discontinuous fashion. This behavior is discussed in terms of the breaking of the hydrogen bonds between OG and P2VP being facilitated by shear.

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