Formation of a Freely Suspended Membrane via a Combination of Interfacial Reaction and Wetting

Abstract

Applying poly(ethoxysiloxane) (a liquid non-water-soluble polymer that can be hydrolyzed and cross-linked by diluted acids) to an air/pH 1 water interface gave rise to thin homogeneous solid layers. These layers were strong enough to be transferable to electron microscopy grids with holes of dimensions up to 150 microm and covered the holes as freely suspended membranes. No homogeneous layers were formed at an air/pH 5 water interface. Brewster angle microscopy images show that the poly(ethoxysiloxane) is not spontaneously forming a wetting layer on water. It initially forms lenses, which slowly spread out within several hours. We conclude that the spreading occurs simultaneously with the hydrolysis and cross-linking of the poly(ethoxysiloxane) and that the reaction products finally assist the complete wetting of the water surface.

All-Silica Colloidosomes with a Particle-Bilayer Shell

“…It was earlier demonstrated that PEOS does not wet the water surface at the initial stage of the contact. 28 During the hydrolysis, the solubility of PEOS in hydrocarbon is reduced and its affinity to water increases. Therefore, the structure of hydrolyzed PEOS resembles that of the amphiphilic surfactant molecules.…”

Self‐Templating Amphiphilic Polymer Precursors for Fabricating Mesostructured Silica Particles: A Water‐Based Facile and Universal Method

“…Monomeric silanes partially substituted with ethylene glycols are expected to be amphiphilic; however, no information on their assembly in water is available, probably due to their high water solubility and too fast hydrolysis. Therefore, we have chosen a strategy to modify a bulky silica precursor polymer – hyperbranched polyethoxysiloxane (PEOS),7 which possesses much lower water solubility and hence a rather slower hydrolysis rate than the monomer tetraethoxysilane, and shows clear advantages for design of complex silica materials 8. As PEOS contains many terminal ethoxy groups, the substitution degree (subsequently the amphiphilicity) can be fine‐tuned in a broad range.…”

The Power of Non-Hydrolytic Sol-Gel Chemistry: A Review

“…It has a lower solubility in water and lower hydrolysis rates in comparison to tetraethoxysilane. Owing to these features, this polyethoxysiloxane was used as a precursor for the hydrolytic synthesis of silica membranes [123] and mesostructured silica particles [124][125][126].…”