The nitrogen desorption data were used to calculate the pore size distribution (PSD, differential f V(R)~dV p/dR and f S(R)~dS/dR) using the self-consistent regularization (SCR) procedure under non-negativity condition (f V(R) ≥ 0 at any pore radius R) at the fixed regularization parameter α = 0.01. ![]() Assuming the cylindrical shape of pores, the average pore radius was calculated as R = 2V p/S BET. The total pore volume (V p) was equal to that of liquid nitrogen adsorbed at p/p o ≈ 0.98 (p and p o denote the equilibrium and saturation pressure of nitrogen at −195.8 ☌, respectively). The specific surface areas (S BET) were calculated from the isotherms using the Brunauer–Emmett–Teller (BET) method. The low-temperature (−195 ☌) isotherms of nitrogen adsorption/desorption were measured using an ASAP 2010 adsorption analyzer (Micromeritics). The second component can be added in the sol or gel stage using specific processes, e.g., hydrothermal treatment (HTT) or mechanochemical treatment (MChT). However, a new, attractive method of obtaining such silicas can be the use of SiO 2 additive of various origins and structures in the selected stage of the traditional sol–gel procedure. ![]() Such materials are prepared using, for example, polystyrene latex spheres, a novel block of copolymers and templates (an ionic liquid surfactant), or close-packed polystyrene beads, octadecyltrimethylammonium chloride (template), and tetraethoxysilane (TEOS). A special case is materials with an ordered structure and those characterized by multimodal porosity. With so many applications, a very important challenge for materials science is the development of a SiO 2 preparation method with diverse porous structures and physicochemical properties. Silica belongs to the oxide materials commonly used as efficient adsorbents, phases or phase carriers for gas or liquid chromatography, supports for active phases in catalysis, dispersion agents, and in numerous other applications. Results showed that such a one-step preparation method is convenient and makes it possible to obtain multimodal silicas of differentiated porous structures and surface chemistry. The characterizations were made by application of N 2 adsorption/desorption, SEM imaging, quasi-isothermal thermogravimetry (Q-TG), dynamic thermogravimetry/derivative thermogravimetry/differential thermal analysis (TG/DTG/DTA), and cryoporometry differential scanning calorimetry (DSC) methods. A-50 and A-380 aerosils and wide-porous SiO 2 milled at 300 rpm were used as the additives in the sol stage at 20 ☌, the sol–gel stage followed by hydrothermal modification (HTT) at 200 ☌, or in the mechanochemical treatment (MChT) process. In this paper, multimodal silicas obtained using different additives are presented. ![]() Properties of silica materials depend largely on different features: crystal structure, dispersity, surface composition, and porosity as well as the method of preparation and possible modification. The formation of hierarchical, multimodal porosity materials with controlled shape and size of pores is the essential challenge in materials science.
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