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

Light scattering study of salt-free "polyelectrolyte behaviour" of monotelechelic ionomers in a polar solvent

Salt-free polyelectrolyte behaviour which is typically observed at low polymer concentrations for polyelectrolyte aqueous solutions and random ionomer non-aqueous solutions (in polar solvents) (i.e., negative angular dependence of the reciprocal scattering in static light scattering and an appearance of the fast mode in dynamic light scattering) has been observed for monotelechelic ionomer solutions in a polar solvent. This indicates that only single charge (per chain) is sufficient to produce intermolecular electrostatic interactions, which are responsible for such characteristic behaviour. However, the 'characteristic' behaviour, which is typically observed at higher concentrations for polyelectrolyte and random ionomer solutions (i.e., large positive apparent radius of gyration in static scattering and appearance of the slow mode in addition to the fast mode in dynamic scattering) has not been observed to date for monotelechelic ionomer solutions. The absence of high-concentration characteristics for the monotelechelic ionomer solutions gives additional insight as to the nature and structure of 'heterogeneities' in salt-free polyelectrolyte solutions, which is still controversial

Microstructure and mineralogy of lightweight aggregates manufactured from mining and industrial wastes

The microstructure and mineralogy of lightweight aggregates manufactured with washing aggregate sludge, sewage sludge and a clay-rich sediment have been studied. The mineralogical analysis revealed the neo-formation of plagioclase and pyroxene group minerals and a minor presence of gehlenite. Some relationships may be established: (i) heating temperature and dwell time affect the formation of new porosity; (ii) the disappearance of pyroxenes could produce changes in the density of the solid material in the lightweight aggregates; (iii) when an external glassy film is not present, water absorption values depend on the size and number of each type of pore

Facile Preparation of Macroscopic Soft Colloidal Crystals with Fiber Symmetry

A facile, efficient way to fabricate macroscopic soft colloidal crystals with fiber symmetry by drying a latex dispersion in a tube is presented. A transparent, stable colloidal crystal was obtained from a 25 wt % latex dispersion by complete water evaporation for 4 days. The centimeter-long sample was investigated by means of synchrotron small-angle X-ray diffraction (SAXD). Analysis of a large number of distinct Bragg peaks reveals that uniaxially oriented colloidal crystals with face-centered cubic lattice structure were formed. The measurement of evaporation rates under different conditions indicates that the water evaporates primarily through the optically clear regions (i.e., via the solid material) even when the region is more than 2 mm thick