Anomalous Pore Expansion of Highly Monodispersed Mesoporous Silica Spheres and Its Application to the Synthesis of Porous Ferromagnetic Composite

Abstract

In this paper, we report on the pore expansion of monodispersed mesoporous silica spheres (MMSS) by a swelling agent incorporation method, by which swelling agents such as various hydrocarbons were incorporated into mesopores. Mesopores were expanded to more than twice the size (5.5 nm) of the original one (2.5 nm). In this method, pore expansion of MMSS was achieved while radially ordered hexagonal mesopores with spherical morphology and high monodispersity were retained. In addition, we have successfully obtained highly monodispersed porous FePtsMMSS composites by incorporating FePt precursors into the pore-expanded MMSS. The composites had both ferromagnetic behavior with coercivity of 3.3 kOe at room temperature and mesoporosity with pore volume of 0.74 cm 3 g -1 , which is enough to incorporate a variety of chemicals, nanoparticles, and proteins, such as drugs, quantum dots, enzymes, and DNA molecules. They have potential applications in drug delivery systems, gene delivery systems, magnetic hyperthermia treatments, and magnetic photonic crystals.

Preparation of dandelion-type silica spheres and their application as catalyst supports

“…The addition of TEOS and ethanol to the solution containing micelles of surfactants with stirring initiates the formation of silica spheres whose mesopores are formed toward their centers [9]. Hexadecyltrimethylammonium bromide (CTAB) is a typical surfactant used in the preparation of mesoporous silica spheres [10,11]. The replacement of ethanol by acetone is also effective in producing mesopores in silica spheres with high reproducibility [12,13].…”

Colloidal‐Crystal Laser Using Monodispersed Mesoporous Silica Spheres

“…[26][27][28] Moreover, since fine mesopores, which exist in a radial pattern, account for 40-60% of the volume of MMSSs, these are capable of adsorbing a large amount of fluorescent materials and functional nanoparticles. [29][30][31] A colloidal crystal consisting of MMSS with fluorescent materials adsorbed in the mesopores is expected to be an optical resonator due to the Bragg reflection, and the fluorescent materials introduced into mesopores of the particles would function as a lasing medium. An MMSS colloidal-crystal laser is superior to other types of colloidal-crystal lasers reported so far because it does not consist of multiple components; furthermore, since its ordered structure is self-organized, it is very easy to produce.…”

Silicon oxide based materials for controlled release in orthopedic procedures

“…Swelling agents (such as alkanes/EtOH mixture) can expand the pore diameter up to 6.0 nm [80]. Another principle to expand the pore size of MSN is by a post-synthesis hydrothermal treatment that exchanges surfactant with a longer alkylchain length [81,82]. For sol-gel silica prepared without surfactant, the pore size can be adjusted by varying the pH of the sol [83,84].…”