Uniform Pores in Cross-Linked Polymers by Dispersed Fumed Silica Templating

Abstract

Hydrophobic fumed silica dispersions in organic monomers were explored as a pore-forming system in polymer synthesis. The method developed provides a simple and effective way of controlling the pore size in highly cross-linked polymers. Fumed silica suspensions in divinylbenzene were polymerized with subsequent etching of the silica particles, therefore creating the porosity in the polymer. The resulting polymers are mesoporous materials, exhibiting an extremely narrow pore size distribution with an average pore size of about 100 Å, replicating the size of the nanofiller. BET surface areas were found appreciably high (∼350 m2/g). Furthermore, the rheological behavior of the prepolymerization mixtures was studied to elucidate the formation of the porous network and showed that a tridimensional network of particles is formed at a minimum silica fraction (Φ v ) of 0.08.

Molecularly imprinted polymers synthesized via template immobilization on fumed silica nanoparticles for the enrichment of phosphopeptides

“…Given the starting average particle size of the fumed silica of 120 Å and considering the surface modifications, this result seems consistent with previous reports. 24 By contrast, MIP3 and NIP3 exhibit a dual pore size distribution which we ascribe to the use of THF, resulting in a fraction of smaller pores (micropores). This result shows that even a small amount of liquid solvent is detrimental for the homogeneity of the pores.…”

“…Recently, a new route for controlling the porosity in highly crosslinked divinylbenzene (DVB) polymers 24 and MIPs imprinted with ephedrine has been reported. 25 In this method, the synthesis of MIPs is performed in the absence of a solvent using dispersed fumed silica nanoparticles in a templating approach to create the internal porosity of the polymer.…”

Solvent‐free synthesis of chiral molecularly imprinted polymers: Porosity control using a nano‐sized solid porogen

“…The compatibility of a very hydrophobic cross‐linker, such as the divinylbenzene used in this synthesis, with hydrophobic surface modified fumed silica allows for the incorporation of a sufficient volume of silica particles in the pre‐polymerization mixture which results in reasonably high pore volumes (>0.5 mL/g). However, we have previously studied this parameter using a composition of divinylbenzene without any other co‐monomers and were able to obtain a larger pore volume, which is due to a higher percolation threshold . Hence, the presence of more hydrophilic monomers may require an assessment of the possible surface modifications on the silica.…”

“…In a previous study we have concluded that fumed silica can function as a solid porogen in cross‐linked polymers synthesis . The non‐imprinted poly(divinylbenzene) materials were mesoporous materials with high surface areas and the silica particle size was replicated in the polymer average pore size.…”

Porous Polymer Membranes by Hard Templating – A Review

“…[162] After polymerization and removal of the fumed silica, closely controlled and interconnected pores were formed. The fumed silica, starting from monodisperse primary silica particles allowed precise pore size control in a random setting of aggregates avoiding the tedious step of aligning a colloid.…”