RESUMEN
In this work, organic aerogels from spent ground coffee and apple pomace were prepared and characterized for the first time. Apple aerogel was found to be much lighter than that from coffee (0.19 vs. 0.016 g/cm3, whereas the specific surface areas are comparable (229 vs. 208 m2/g). Being intrinsically hydrophilic, these aerogels were silanized, both in liquid and gas phase, to increase stability in aqueous media. The latter modification method allowed chemical grafting of the silane to the aerogel surface (evidenced by FTIR and TGA) and resulted in certain hydrophobicity, as was evidenced via contact angle measurements: both aerogels possess a contact angle of ca. 100° after the gas hydrophobization, while for the pristine aerogels it was 50°. Furthermore, it was observed that the gas-phase silanization process is more applicable to apple aerogels.
RESUMEN
Protein aerogel particles prepared by supercritical-CO2-drying (SCD) of ground whey protein (WP) hydrogels (20% w/w, pH 5.7) were converted into oleogels by dispersion in selected edible oils (castor, cod liver, corn, flaxseed, MCT, peanut and sunflower oil). The obtained oleogels were analysed for oil content, microstructure, rheological properties, and ATR-FTIR spectra. Except for castor oil, solid-like, plastic materials with comparable composition (80% oil, 20% WP) and rheological properties (G'~3.5 × 105 Pa, Gâ³~0.20 × 105 Pa, critical stress~800 Pa, tanδ~0.060) were obtained. Optical and confocal microscopy showed that the generated structure was associated with the capillary-driven absorption of oil into the porous aerogel particles interconnected via particle-particle interactions. In this structure, the oil was stably entrapped. Results evidenced the reduced role of edible oil characteristics with the exception of castor oil, whose high polarity probably favoured particle-oil interactions hindering particle networking. This work demonstrates that WP aerogels could be regarded as versatile oleogel templates allowing the structuring of many edible oils into solid-like materials.
RESUMEN
A facile deposition method of 3D photonic crystals made of yttrium-stabilized zirconia (YSZ) was developed. YSZ nanoparticles with primary particle size below 10 nm and cubic crystalline phase were synthesized by hydrothermal treatment of solutions of zirconyl nitrate, yttrium nitrate and acetylacetone. Before coassembly with polystyrene (PS) microspheres, a dispersant Dolapix CE64 was added to the dialyzed sol of YSZ nanoparticles to render their surface negatively charged. Vertical convective coassembly resulted in 3D ordered YSZ/PS hybrid films, which were inverted at 500 °C in air to produce inverse opals. The linear shrinkage of the coatings was in the range 15-20%, below previously reported values for YSZ. The obtained coatings demonstrated pronounced photonic properties and retained their ordered structure after annealing at 1000 °C for 2 h. Increasing the filling fraction of crystalline nanoparticles in the templates should enable production of fully functional 3D photonic crystals for applications in high-temperature photonics.