Hexagonally Perforated Layer Morphology in PS-b-P4VP(PDP) Supramolecules

Supramolecular complexes of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers and small molecules such as pentadecylphenol (PDP) have been studied extensively in recent years. In the present study, PS-b-P4VP(PDP) complexes with a minority P4VP(PDP) block are morphologically characterized focusing on the region between the lamellar and cylindrical phase. Dynamic mechanical measurements and small-angle X-ray scattering are used to follow the transitions between the ordered states upon heating/cooling. The self-assembled state at various temperatures is determined by small-angle X-ray scattering and transmission electron microscopy. In contrast to the opposite case of majority P4VP(PDP) blocks, where the transition from lamellar to cylindrical structures frequently occurs via the gyroid morphology, the complexes adopt the hexagonally perforated layered morphology in a broad range of compositions. Although known as a metastable phase in pure diblock copolymers, the hexagonally perforated layered phase appears as an equilibrium phase in PS-b-P4VP(PDP) complexes, being stabilized by the presence of the hydrogen-bonded PDP side chains in the minority component domains

Real-Time Fast Structuring of Polymers Using Synchrotron WAXD/SAXS Techniques

In industrial processes, polymer melts are often exposed to a combination of fast cooling rates, high flow fields, and high pressures. The processing conditions have an ultimate impact on the structure that develops during cooling. The final structure at the nano- and microscopic level determines the properties of the final polymer product. Small and wide angle X-ray scattering and diffraction (SAXS/WAXD) are the best techniques for investigating in-situ and real-time fast polymer structuring at a scale ranging from 0.1 to 100 nm. This contribution reviews the main quantities that can be extracted from SAXS and WAXD experiments on semicrystalline polymers and shows the most recent results on real-time investigation of polymer structuring with millisecond time resolution. Examples of structuring during fast cooling, flow in confined geometry, and uniaxial stretching are discussed. Future directions for the use of synchrotron SAXS/WAXD to study fast polymer structuring are also discussed

Self-Assembled Poly(4-vinylpyridine)-Surfactant Systems Using Alkyl and Alkoxy Phenylazophenols

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 well-studied 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 (TODT), and the glass transition temperature Tg of the self-assembled systems all increase with increasing alkyl chain length. The correlation between TODT and Tg observed is argued to be the consequence of the increasing segregation in the self-assembled systems with increasing alkyl tail length of the amphiphiles.

Structure development of low-density polyethylenes during film blowing : a real-time wide-angle X-ray diffraction study

Keywords: crystal growth; in situ WAXD; low-density polyethylene; orientation; thin film We studied experimentally the structure development during film blowing for three different low-density polyethylenes at four different processing conditions. For this, we combined blown film extrusion with in situ X-ray diffraction at a synchrotron radiation beam line. The measurements were performed at rheological similar conditions at the die exit, with each grade possessing different molecular properties in terms of molecular weight distribution and branching content. The development of crystallinity and molecular orientation was determined as function of the distance from the die. It is shown that this approach provides a valuable method to study structure evolution during film blowing and can be used to validate results from numerical models and help to improve and/or extend these models

Nanoscale Conducting Cylinders Based on Self-Organization of Hydrogen-Bonded Polyaniline Supramolecules

Comb-shaped or hairy rodlike supramolecules can be obtained by hydrogen bonding rigid rod polymers and amphiphilic oligomers. Here we introduce a concept to achieve electrically conducting acid doped PANI to allow cylindrical self-organization. PANI is doped with camphorsulfonic acid (CSA) where 4-hexylresorcinol (Hres) is hydrogen bonded to form supramolecules, which further undergo self-organization. The structure formation of PANI(CSA)0.5(Hres)y complexes is discussed on the basis of small- and wide-angle X-ray scattering and electrical conductivity. Highly ordered hexagonal cylindrical structures were observed with a distance between the cylinders around 35 Å. Electrical conductivity increases 2 orders of magnitude upon formation of cylindrical structures, potentially due to confinement of PANI chains within the cylinders. The method would then allow an easy preparation of nanoscale organic conducting wires, just by mixing the components together.