Spherical Pseudo‐Inverse Opal Silica with Pomegranate‐Like Polymer Microparticles as Templates

Abstract

Spherical silica particles with pseudo‐inverse opal structure are synthesized by using pomegranate‐like polymer microparticles as templates. A micro‐dispersion polymerization occurring in the suspended monomer droplets in the presence of a silica precursor leads to the formation of nearly monodisperse polymer sub‐particles of about 1 µm size, randomly‐packed within a 30–100 µm polymer particle. The polymerization is followed by an acid‐catalyzed reaction that induces formation of silica in the interstices between the sub‐particles within a polymer particle. Spherical PIOS particles are eventually produced by selectively removing the polymer template by pyrolysis. The PIOS particles show large specific surface areas with unique pore geometry and pore size distribution.magnified image

Polymerization of Ethylene over rac-Et(1-indenyl)2ZrCl2/MAO Catalyst Supported on Pseudo-Inverse Opal Silica Particles

“…The surface area of the PIOS particles is about 78–93% larger than the two commercial silica samples employed in this study. The PIOS particles and the commercial silica particles were completely amorphous as confirmed by the X-ray diffraction (XRD) patterns …”

“…The template polymer particles can be synthesized by a modified suspension polymerization called microdispersive suspension polymerization where subparticle nucleation and growth are induced by controlling the thermodynamic solution conditions within suspended monomer/solvent droplets. The procedure to make PIOS particles has been reported in our previous work . The typical synthesis process for PIOS particles is illustrated in Figure a.…”

“…The organic droplets (10–150 μm) were stabilized by a small amount of partially hydrolyzed poly(vinyl alcohol) dissolved in the aqueous phase (89% hydrolyzed, MW = 85 000–124 000 g/mol). The initial composition of MMA– n -hexane mixture is chosen such that the PMMA produced precipitates in the liquid phase within suspended droplets . During the polymerization, polymer particles precipitate out from the liquid phase within suspended droplets.…”

“…The procedure to make PIOS particles has been reported in our previous work. 24 The typical synthesis process for PIOS particles is illustrated in Figure 1a. Here, the three step preparation procedure involves (i) the synthesis of unique pomegranate-like microparticle templates containing a silica precursor (SiC 8 H 20 O 4 , tetraethyl orthosilicate; TEOS) by modified suspension polymerization, (ii) the impregnation of the polymer microparticles with a sol−gel catalyst to induce the hydrolysis/condensation of TEOS within polymer microparticles, and (iii) the selective removal of the polymer by pyrolysis to obtain PIOS particles.…”

Ethylene Polymerization over Metallocene Catalysts Supported on Highly Fibrous Silica Nanoparticles

“…Among these, the mesoporous silica materials with controlled pore size and pore volume have been illustrated to accommodate large metallocene catalysts better than conventional porous microsilica particles. Pseudoinverse opal silica (PIOS) microparticles that have unique morphology have been found to offer excellent access to “egg‐shell”‐like silica surfaces for the catalyst components and monomers . These PIOS particles can be derived from a modified suspension polymerization process.…”