Selective Surface Modification of SiO₂−TiO₂ Supports with Phosphonic Acids

Abstract

The selective surface modification by phosphonic acids of SiO 2 -TiO 2 supports at the micrometer and molecular scale was investigated. Under aqueous conditions, phosphonic acids bind to TiO 2 and not to SiO 2 surfaces. A micropatterned support was prepared by electron beam microlithography and selectivity, of the surface modification was evidenced using scanning Auger electron spectroscopy (SAES). The second support was a mesoporous SiO 2 -TiO 2 mixed oxide (10 mol % Ti) epoxidation catalyst prepared by sol-gel processing. Selectivity was deduced from the decrease of the catalytic activity upon modification and from chemical analysis; bonding modes to the surface were investigated using solid-state 29 Si and 31 P MAS NMR. The possibility to introduce different organic groups by successive treatments with a phosphonic acid and a silylating agent was illustrated in the case of the mixed oxide.

Aqueous or solvent based surface modification: The influence of the combination solvent – organic functional group on the surface characteristics of titanium dioxide grafted with organophosphonic acids

“…They are applied in membranes [1], organic thin-film transistors [2], solar cells [3], chromatography [4,5], transparent nanocomposites [6], for the immobilization of bioactive molecules [7] and other technologies. A method for surface functionalization is modification with organophosphonic acids (PAs) or their derivatives [8][9][10][11]. Surface functionalised with a full monolayer of organophosphonic acids has a higher hydrolytic stability (pH 1-10) as for the functionalisation with organosilanes [12].…”

Electrochemical Immunosensor Using the Modification of an Amine-functionalized Indium Tin Oxide Electrode with Carboxylated Single-walled Carbon Nanotubes

“…Derivatives of phosphonic acid that undergo easy formation of organic monolayers on metal oxide surfaces are useful for introducing polar functional groups on the surfaces. 19,20 Contact angle measurement (Figure 2) reveals that water contact angle decreases with the formation of an amine-functionalized monolayer. The contact angle plateaus, and 24-h immersion is enough to form a monolayer on ITO electrodes.…”

Physics and Chemistry of Sol-Gel Nanocomposites Formation

“…The following heteroelements are usually impregnated in silicate matrices: aluminum [194,195], 4.4 Hybrid Nanocomposites Based on Heteroelemental Oxide/Oxide Ceramicszirconium [196,197], calcium [33,88,198], iron [199], palladium [200], phosphate-ions [201], etc. However, most popular is already mentioned ceramic mixture of Si-Ti, Ti-Zr oxides [202][203][204][205][206][207][208][209][210][211][212][213]. Sol-gel synthesis was performed at low temperatures and makes it possible to realize strict control over ratio of elements and their homogenous distribution in formed nanocomposites.…”