Magnetic Neutron Scattering in Reduced Graphene Oxide

The scale of magnetic correlations in materials based on reduced graphene oxide (RGO) has been estimated for the first time using the method of small-angle scattering of polarized neutrons. This information cannot be obtained by other methods. Experiments have demonstrated the presence of small-angle magnetic-nuclear interference scattering for both original RGO and an RGO-based composite in magnetized fields H about 1 T, which unequivocally indicates the presence of magnetized areas on the scale of 1000 Å in the studied materials

Mesostructure of Composite Materials Based on Segmented Poly(Urethane Imide) Containing Ferrite Nanoparticles

The mesostructure of segmented poly(urethane imide) containing 4–10 wt % CoFe2O4 orAl3Fe5O12 nanoparticles was experimentally studied by small-angle polarized neutron scattering, which cananalyze the nuclear and magnetic subsystems of the obtained composites. The transformation of the domainstructure of the magnetic elastomers based on poly(urethane imide) was investigated at various concentra-tions, chemical compositions, and localizations of ferrite nanoparticles in polymer chains. The dynamics ofthe change in the segmental mobility of soft blocks during heating of samples was characterized by magnetic–nuclear interference scattering. The experiments detected changes in the supramolecular structure of themultiblock copolymer, which depended on the percentage and type of nanoparticles. The correlation radiiwere determined in the magnetic subsystem of ferrite nanoparticles embedded in hard aromatic blocks ofpoly(urethane imide) as nodes of intermolecular crosslinkers and chain extenders. The temperature depen-dence was analyzed for the intensity of small-angle nuclear scattering by poly(urethane imide) and magneticelastomers based on it, under the conditions of the transition of soft aliphatic segments from the glassy to thehighly elastic state

Morphological structure of Gluconacetobacter xylinus cellulose and cellulose-based organic-inorganic composite materials

Scanning electron microscopy, ultra-small-angle neutron scattering (USANS), small-angle neutron and X-ray scattering (SANS and SAXS), as well as low-temperature nitrogen adsorption, were used in the studies of micro- and mesostructure of polymer matrix prepared from air-dry preliminarily disintegrated cellulose nano-gel film (synthesized by Gluconacetobacter xylinus) and the composites based on this bacterial cellulose. The composites included ZrO2 nanoparticles, Tb3+ in the form of low molecular weight salt and of metal-polymer complex with poly(vinylpyrrolydone)-poly(methacryloyl-o-aminobenzoic acid) copolymer. The combined analysis of the data obtained allowed revealing three levels of fractal organization in mesostructure of G. xylinus cellulose and its composites. It was shown that both the composition and an aggregation state of dopants have a significant impact on the structural characteristics of the organic-inorganic composites. The composites containing Tb3+ ions demonstrate efficient luminescence; its intensity is an order of magnitude higher in the case of the composites with the metal-polymer complex. It was found that there is the optimal content of ZrO2 nanoparticles in composites resulting in increased Tb3+ luminescence

Temperature-responsive star-shaped poly(2-ethyl-2-oxazoline) and poly(2-isopropyl-2-oxazoline) with central thiacalix[4]arene fragments: structure and properties in solutions

Temperature-responsive star-shaped poly(2-ethyl-2-oxazoline) (star-PETOX) and poly(2-isopropyl-2-oxazoline) (star-PIPOX) with arms grafted to the lower rim of thiacalix[4]arene were studied in solutions by viscometry, sedimentation velocity, light scattering, and small-angle neutron scattering. The experiments were carried out in water and tetrahydrofuran solutions. It was revealed that in tetrahydrofuran, the studied polymers were present only as individual molecules, while in aqueous solutions, in addition to individual molecules, large polymer aggregates were found. Molecular characteristics of the star-PETOX and star-PIPOX samples were estimated; their behavior in tetrahydrofuran and water was studied over a wide temperature range. It was established that a cloud point of the aqueous solution of star-PETOX (67 °C) is higher than that of a solution of star-PIPOX (35 °C). Comparison of the data obtained by dynamic light scattering and small-angle neutron scattering turned out to be fruitful in revealing all the structural levels of the organization of star-PETOX and star-PIPOX in aqueous solutions. They include the level of the individual macromolecules and the level of supramolecular organization with a star-like architecture