Catalytically Active SiO Aerogels Comprising Chelate Complexes of Palladium.

A series of silica-based aerogels comprising novel bifunctional chelating ligands was prepared. To produce target aerogels, two aminosilanes, namely (3-aminopropyl)trimethoxysilane (APTMS) and -(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS), were acylated by natural amino acids (()-(+)-2-phenylglycine or -phenylalanine), followed by gelation and supercritical drying (SCD). Lithium tetrachloropalladate was used as the metal ion source to prepare strong complexes of Pd with amino acids covalently bonded to a silica matrix.

Study of Precipitates in Oxide Dispersion-Strengthened Steels by SANS, TEM, and APT.

In this work, the nanostructure of oxide dispersion-strengthened steels was studied by small-angle neutron scattering (SANS), transmission electron microscopy (TEM), and atom probe tomography (APT). The steels under study have different alloying systems differing in their contents of Cr, V, Ti, Al, and Zr. The methods of local analysis of TEM and APT revealed a significant number of nanosized oxide particles and clusters.

Composite Hydrogels Based on Bacterial Cellulose and Poly-1-vinyl-1,2,4-triazole/Phosphoric Acid: Supramolecular Structure as Studied by Small Angle Scattering.

New composite hydrogels (CH) based on bacterial cellulose (BC) and poly-1-vinyl-1,2,4-triazole (PVT) doped with orthophosphoric acid (oPA), presenting interpenetrating polymeric networks (IPN), have been synthesized. The mesoscopic study of the supramolecular structure (SMS) of both native cellulose, produced by the strain , and the CH based on BC and containing PVT/oPA complex were carried out in a wide range of momentum transfer using ultra- and classical small-angle neutron scattering techniques. The two SMS hierarchical levels were revealed from 1.

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica.

The chemical immobilization of cobalt(II) ions in a silica aerogel matrix enabled the synthesis of the first representative example of aerogel-based single-ion magnets. For the synthesis of the lyogels, methyl-trimethoxysilane and N-3-(trimethoxysilyl)propyl ethylenediamine were co-hydrolyzed, then the ethylenediamine groups that were immobilized on the silica matrix enabled the subsequent binding of cobalt(II) ions. Lyogels with various amounts of ethylenediamine moieties (0.

Domain Structure, Thermal and Mechanical Properties of Polycaprolactone-Based Multiblock Polyurethane-Ureas under Control of Hard and Soft Segment Lengths.

A series of multiblock polyurethane-ureas (PUU) based on polycaprolactone diol (PCL) with a molecular mass of 530 or 2000 g/mol, as well as hard segments of different lengths and structures, were synthesized by the step-growth polymerization method. The chemical structure of the synthesized multiblock copolymers was confirmed by IR- and NMR-spectroscopy. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were used to determine the relaxation and phase transition temperatures for the entire series of the obtained PUU.

The first amorphous and crystalline yttrium lactate: synthesis and structural features.

The synthesis and crystal structure of the first molecular yttrium lactate complex, Y(Lac)(HO), is reported, where the coordination sphere of yttrium is saturated with lactate ligands and water molecules, resulting in a neutral moiety. In Y(Lac)(HO), hydrogen bonding between α-hydroxy groups and water molecules allows for the formation of 2D layers. A subtle variation in synthetic conditions, a slight increase in pH (5.

Calcifying Bacteria Flexibility in Induction of CaCO Mineralization.

Microbially induced CaCO precipitation (MICP) is considered as an alternative green technology for cement self-healing and a basis for the development of new biomaterials. However, some issues about the role of bacteria in the induction of biogenic CaCO crystal nucleation, growth and aggregation are still debatable. Our aims were to screen for ureolytic calcifying microorganisms and analyze their MICP abilities during their growth in urea-supplemented and urea-deficient media.

Crystal and Supramolecular Structure of Bacterial Cellulose Hydrolyzed by Cellobiohydrolase from 3C: A Basis for Development of Biodegradable Wound Dressings.

The crystal and supramolecular structure of the bacterial cellulose (BC) has been studied at different stages of cellobiohydrolase hydrolysis using various physical and microscopic methods. Enzymatic hydrolysis significantly affected the crystal and supramolecular structure of native BC, in which the 3D polymer network consisted of nanoribbons with a thickness ≈ 8 nm and a width ≈ 50 nm, and with a developed specific surface ≈ 260 m·g. Biodegradation for 24 h led to a ten percent decrease in the mean crystal size of BC, to two-fold increase in the sizes of nanoribbons, and in the specific surface area up to ≈ 100 m·g.

Luminescence of Eu ions in hybrid polymer-inorganic composites based on poly(methyl methacrylate) and zirconia nanoparticles.

Spherical nanoparticles of ZrO with 2 and 10 mol% EuO up to 20 nm size were prepared by the method of hydrothermal synthesis for luminescent functionalization of the polymer-inorganic nanocomposites based on poly(methyl methacrylate). Surface modification of oxide nanoparticles was carried out by 3-(trimethoxysilyl)propyl methacrylate, dimethoxymethylvinyl silane and 2-hydroxyethyl methacrylate to provide uniform distribution and to prevent agglomeration of nanosized filler in the polymer matrix. Polymer-inorganic composites were synthesized by in situ free radical polymerization in bulk.

Combined SANS and SAXS study of the action of ultrasound on the structure of amorphous zirconia gels.

In the present work, we have studied for the first time the combined effect of both sonication and precipitation pH on the structure of amorphous zirconia gels synthesized from zirconium(IV) propoxide. The techniques of small-angle neutron and X-ray scattering (SANS and SAXS) and low temperature nitrogen adsorption provided the integral data on the changes in the microstructure and mesostructure of these materials caused by ultrasonic (US) treatment. Amorphous ZrO2·xH2O synthesized under ultrasonic treatment was found to possess a very structured surface, characterized by the surface fractal dimension 2.