Scalable synthesis of smooth PS@TiO2 core-shell and TiO2 hollow spheres in the (sub) micron size range: understanding synthesis and calcination parameters

Abstract

Hollow spheres made from titanium dioxide (TiO 2) are interesting structures because of their high surface area and low density, combined with semiconducting properties of the TiO 2. However, the synthesis is still challenging because of the high reactivity of the titania precursors. Here, we present a simple, reproducible, and scalable way to synthesize TiO 2 hollow spheres in the micrometer/sub-micrometer size range comprising three steps: synthesis of polystyrene template particles, growth of TiO 2 shells, and calcination to hollow spheres. We investigate the importance of adjusting the seed particle surface functionalization via the appropriate choice of comonomer during the dispersion polymerization. An aging step and a calcination process at low temperatures are mandatory to retain the particle integrity during the seed particle removal. We provide a detailed characterization of each step of this process including electron microscopy, small angle X-ray scattering, and simultaneous thermal analysis.

Carbothermal synthesis of micron‐sized, uniform, spherical silicon carbide (SiC) particles

“…The shrinkage behavior of metal oxide precursors is already known; for example, Chen et al [22] . noticed shrinkage of 21 % after thermal conversion of C/SiO 2 to SiC aerogels and Lechner et al [38] . determined a reduction of up to 18 % by calcination of TiO 2 to anatase.…”

“…The shrinkage behavior of metal oxide precursors is already known; for example, Chen et al [22] noticed shrinkage of 21 % after thermal conversion of C/SiO 2 to SiC aerogels and Lechner et al [38] determined a reduction of up to 18 % by calcination of TiO 2 to anatase. The size reduction is related to the release of gaseous species during the transformation process, particularly H 2 O and CO, leading to a higher density and a considerable mass loss.…”

Prolate spheroidal polystyrene nanoparticles: matrix assisted synthesis, interface properties, and scattering analysis

“…In both positively charged particle syntheses, the positively charged co-monomer 2-methacryloxyethyl-trimethyl-ammoniumchloride (MTC) and neutral polyvinylpyrrolidone (PVP) were added to increase the steric stability. The recipe for the dispersion polymerisation for positively charged particles can be found in Lechner et al 42…”

Three-Dimensional Giant Invisibility to Superscattering Enhancement Induced by Zeeman-Split Modes

“…In case of null B 0 , InSb turns isotropic with ϵ 1 (0) ≡ ϵ 3 and ϵ 2 (0) = 0. For experimental implementation, core-shell spheres in the micrometer size range, consisting of dielectric cores and semiconductor coatings, can be practically synthesized by shell growth condensation reaction methods . In addition, the external magnetic field and the entire experimental procedure, can be routinely carried out using magnet-based setups. , In the present case, the spherical setup is illuminated by a transverse electric (TE) plane wave, that is, the incident electric field E inc is normal to the plane of incidence; therefore, if the plane of incidence is the yz -plane as shown in Figure a, then E inc is x -polarized and the indicent wavevector is normal to B 0 .…”