Design of a New Invertible Polymer Coating on a Solid Surface and Its Effect on Dispersion Colloidal Stability

Abstract

This article presents a new approach to building up self-adjustable invertible polymer coatings at solid surfaces. The approach is based on a two-step process. In the first step, the surface of dispersed TiO2 or silicon wafers was functionalized with the aid of a reactive copolymer, viz., poly(styrene-alt-maleic anhydride) (PSM), to which, in the second step, the chains of amphiphilic oligoester have been tethered. The latter contains both hydrophilic poly(ethylene glycol) and hydrophobic aliphatic dibasic acid moieties being alternately distributed along the oligomer chains. It is shown that the titania modified in this way can form stable suspensions in both polar (water) and nonpolar (toluene) media. Moreover, multiple drying/redispersion cycles demonstrate the ability of the modified titania particles, after their removal from one type of dispersion and consequent drying, to be redispersed in dispersing media strongly differing by polarity from that of the previous medium. An environmentally induced switching of the surface properties has been observed via the measurement of the wetting contact angles and scanning force microscopy (SFM) of silicon wafers covered by PSM with tethered oligoester chains. These experiments give strong support for the predicted capability of such polymer coatings to switch their environmental appearance (i.e., to behave as a self-adjustable invertible interface because of the ability of the tethered amphiphilic oligoester chains to change their conformations in response to environmental changes in such a manner so as to adapt and enhance their compatibility with the surrounding media).

Visible light photoactive titanium dioxide aqueous colloids and coatings

“…Functionalization by organic compounds may be used to increase the dispersibility in liquids and formation of stable colloidal solutions, but also to improve compatibility with solids, e.g., polymer matrices [1]. Physical properties of particles in suspensions strongly depend on charge distribution and ionic structure at the particle-solvent interface [2,3].…”

Plasma treatment of hydrophobic sub-layers to prepare uniform multi-layered films and high-performance gas separation membranes

“…Surface morphology and bulk chemical structures of BTESO coatings on Me-SiO 2 films seemed unchanged after plasma treatment. Kohut et al [36] found that amphiphilic oligoester with hydrophilic and hydrophobic chains behaved as a self-adjustable interface, changing the confirmation to adapt to and enhance compatibility with surroundings polar or non-polar media. BTESO sols also have the structures that contained both hydrophilic and hydrophobic portions.…”

Three-dimensional Numerical Analysis of a Joint Bonded Reinforced with Silica Nanoparticles (SiO2)

“…here is an increasing interest in polymer/silica nanocomposites for the developments of new materials with improved thermal and mechanical properties [1][2][3]. Polymer nanocomposites are among the most promising materials.…”