Self-Assembled Monolayers of Alkylphosphonic Acids on Metal Oxides

Abstract

Dense, highly ordered monolayers can be prepared by the adsorption of octadecylphosphonic acid (ODPA) onto nonporous ZrO2, TiO2, and zirconated silica powders. ODPA reacts strongly with Al2O3 to form a bulk (aluminoalkyl)phosphonate. The infrared spectra of the ODPA monolayers indicate a degree of conformational order comparable to self-assembled monolayers on planar substrates. From the solid-state 31 P and 13 C NMR spectra, the strength of the surface interaction and the degree of conformational order decrease in the following order: zirconated silica > ZrO2 > TiO2. Although the inner methylenes are primarily in an all-trans conformation, the chain termina are highly disordered. In the case of zirconated silica, there is evidence for the formation of some bulk zirconium alkylphosphonate. Proton line width measurements from 2D WISE NMR experiments reveal that considerable chain mobility is present in the ODPA monolayers on ZrO 2 and TiO2, in contrast to bulk crystalline phases.

Molecular Simulation of the Interlayer Structure and the Mobility of Alkyl Chains in HDTMA+/Montmorillonite Hybrids

“…This also has been found in other experimental studies of adsorption organics onto the surface and mesopores of various materials. [39][40][41] However, detailed information about the mobility of alkyl chains and individual atoms on alkyl chain is difficult to obtain by experiment.…”

Selective aluminum passivation for targeted immobilization of single DNA polymerase molecules in zero-mode waveguide nanostructures

“…Similar to nonpolymeric phosphonates, initial electrostatic interactions in solution are likely stabilized in the subsequent dehydration step by the formation of covalent aluminophosphonate bonds (Al-O-P), which are hydrolytically more stable than Si-O-P bonds (23,24,29). To date, phosphonate derivatizations of metal oxide surfaces have predominantly used monophosphonate-terminated alkanes to form SAMs (24,(30)(31)(32)(33) or complex polyethylenglycol-polyalkylphosphonate graft copolymers (34,35). To our knowledge, simple aliphatic polymers containing many phosphonate side groups have not previously been described for protein antifouling applications on metal oxide surfaces.…”

Physical Deposition Assisted Colloidal Lithography: A Technique to Ordered Micro/Nanostructured Arrays

“…These values for the methylene group stretching mode are close to those of a crystalline alkane and are typically taken as evidence of the formation of a dense, well-ordered, self-assembled monolayer of stearic acid on the oxide surface. [106][107][108] Therefore, the photodegradation of stearic acid can be monitor by observing density of these two frequencies. With increasing the UV irradiation time, the vibrational bands of the methylene group gradually decreased and almost completely disappeared after 25 min, as shown in Figure 38a.…”