Polymer-in-a-Silica-Crust Membranes:  Macroporous Materials with Tunable Surface Functionality

Abstract

We report on alkaline hydrolysis of tetraethoxysilane (Stöber synthesis) inside a macroporous polymer matrix resulting in a homogeneous coverage of silica onto the polymer surface. The encapsulation of the polymer struts by a continuous silica crust allows further functionalization with hydrophilic and hydrophobic silylating agents. The porous silica polymeric hybrid material combines the morphological control and mechanical flexibility of the polymeric matrix with the convenient surface modifications developed for glass and amorphous silica. This concept is applied to macroporous membranes where alteration in surface functionality allows tuning of hydrophobicity (contact angle and liquid entry pressure), streaming potential, and adsorption capacity of double-stranded DNA.

Medical applications of membranes: Drug delivery, artificial organs and tissue engineering

“…Extensive review of these topics is beyond the scope of this paper. The reader, however, can find more in research [138,[146][147][148][149][150] and patent literature [151][152][153]…”

Thiol-functionalized silica colloids, grains, and membranes for irreversible adsorption of metal(oxide) nanoparticles

“…Polymeric materials cannot as easily be chemically modified as silica, but it was recently shown that PES membranes can be encapsulated in silica by performing Stöber synthesis directly onto the polymer [23]. Here, we show that the addition of Bindzil silica nanoparticles results in a smooth, complete coverage of the membranes leaving a large silica surface available for functionalization with organosilanes.…”

“…In the first method, amorphous silica was synthesized directly onto the membranes. The PES-membranes were soaked in an ammonia solution (10 mL, 25% in 40 mL ethanol) for approximately 1 h before placing them in between two filter papers soaked in TEOS (10 vol% in ethanol) [23]. To allow the reagents to be homogeneously absorbed, the PES-membranes were carefully blotted, and left for 4 h in a covered Petri dish.…”

The Role of Enzymes in Biomineralization Processes

“…Further current examples are silicacoated polymers that can be produced in all kinds of shapes, similar to diatom cell wall morphologies [225]. The advanced freeze casting process invented by Tomsia and colleagues has been shown to produce three-dimensional laminar structures that look quite similar to mollusk shell nacre or microporous hydroxyapatite [222].…”