Meso-Structuring of SiCN Ceramics by Polystyrene Templates

Abstract

A simple one-pot synthesis of well-defined PS-silazane nano-composites (polystyrene, PS) is described. In contrast to the, thus far, used two-step procedure ((1) assembly of a PS template bed and (2) careful filling of the voids between the PS spheres), which is restricted to macro structuring, we are able to simply mix the PS template and a commercially available silazane precursor HTT-1800 in toluene. The key is the alteration of the zeta potential of the PS template leading to a homogeneous dispersion in the silazane-toluene mixture. Removal of solvent gives rise to a highly ordered PS-silazane nano-composites and subsequent pyrolysis leads to mesoporous silicon carbonitride (SiCN) materials. The one-pot procedure has two advantages: easy upscaling and the use of PS spheres smaller than 100 nm in diameter, here 60 nm. The PS template was characterized by photon correlation spectroscopy, zeta potential measurements, scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). The resulting mesoporous SiCN materials were analyzed by SEM, transmission electron microscopy (TEM), nitrogen sorption analysis, and Fourier transform infrared measurements (FT-IR).

Template‐Free Synthesis of Porous Fe3O4/SiOC(H) Nanocomposites with Enhanced Catalytic Activity

“…8 So far, numerous porous silicon-based ceramics were developed by the PDC route. Using these preceramic polymers, most of the nanoporous PDCs were prepared by a template-assisted technique including hard templates [9][10][11][12][13] and soft templates (block copolymers), [14][15][16] exclusively. Generally, in PDCs, the pores are generated by the evolution of small molecules like CH 4 and H 2 during the pyrolytic conversion process.…”

A Reusable Mesoporous Nickel Nanocomposite Catalyst for the Selective Hydrogenation of Nitroarenes in the Presence of Sensitive Functional Groups

“…Recently, Ewert et al . showed that polystyrene could be used as a soft template to generate a defined mesostructure in SiCN materials.…”

“…[13,14] The silicon carbonitride (SiCN) support is thermally very robust, chemically inert, and attractive for generating rather smallm etal nanoparticles in such supports. [15] In addition, we introduced strategies to mesostructure SiCN [16][17][18] and becamei nterested in combining both approaches to synthesize highlya ctive and selective base-metal catalysts. [19] Herein, we report novel mesostructured Ni@SiCN nanocomposite materials easy to synthesize ands cale up.…”

“…The nickel nanoparticlesa re catalyticallya ctive in the hydrogenation of nitroarenes. For the first time, we show that ar eusableN ic atalyst is able to effect the selectiveh ydrogenation of nitroarenes in the presence of hydrogenation-sensitive functional groups such as C=Cb onds and nitrile,keto, aldehyde, and amide substituents.Recently,E wert et al [17,18] showed that polystyrene couldb e used as as oft template to generateadefined mesostructure in SiCN materials. This strategy of structuring shouldb ec ompatible with the generation of metal-SiCN nanocomposites by transmetalation, crosslinking, and pyrolysis,a sr ecently reported for av ariety of metals.…”

“…Recently,E wert et al [17,18] showed that polystyrene couldb e used as as oft template to generateadefined mesostructure in SiCN materials. This strategy of structuring shouldb ec ompatible with the generation of metal-SiCN nanocomposites by transmetalation, crosslinking, and pyrolysis,a sr ecently reported for av ariety of metals.…”