Molecular dynamics simulations of phosphonic acid–aluminum oxide self-organization and their evolution into ordered monolayers

Abstract

We outline an unprejudiced molecular dynamics simulation approach to study the mechanisms of self-organization encompassing the evolution of surfactant-surface interactions to the growth of self-assembled monolayers (SAMs). Therein, the time-length scale problem is tackled by combining an efficient docking-type procedure for implementing surfactant-by-surfactant association with detailed molecular simulations to explore structural relaxation. For this, nanosecond-scale molecular dynamics simulations unravel ordering processes during the gradual assembly of the monolayer. Along this line, different packing motifs of octadecyl phosphonic acid (ODPA) on the (0001) surface of α-alumina and implications for the final density and ordering of the resulting monolayers are elucidated. Moreover, the role of the solvent is discriminated by comparing SAM formation in 2-propanol, hexane and in a vacuum.

Multifunctional and Tunable Surfaces Based on Pyrene Functionalized Nanoparticles

“…Notably, molecular building blocks based on phosphonic acids (PA) bind covalently to metal oxide surfaces. As such, multifunctional ligands, which feature PAs as surface anchors, are demonstrated to surface immobilize and arrange in a fashion comparable to what is known for self‐assembled monolayers (SAM) of PA derivatives on planar surfaces . Unlike other commonly utilized anchor groups like carboxylic acids PAs do not detach and can thus be stoichiometrically displayed on surfaces .…”

Surface NMR using quantum sensors in diamond

“…5 . With a reference signal, we calibrated our experiment and obtain 0.041 ± 0.003 μT 2 as the signal strength B rms 2 for the monolayer 19 F. This corresponds to a coverage of circa 3 molecules/nm 2 , which is in good agreement with a dense monolayer ( 42 ).…”

Suppressing Antibacterial Resistance: Chemical Binding of Monolayer Quaternary Ammonium Salts to Polymethyl Methacrylate in an Aqueous Solution and its Clinical Efficacy

“…At 10% QAS and higher, the concentration was above the threshold for the free approach to form monolayer QAS on PMMA. Instead, when approaching PMMA, the bulky QAS molecules in higher-concentration solutions restrained one another from binding to PMMA in the necessary orientation, such that the formed Si-O-C bonds were not all fully inclined to the surface [39,51]. This produced the non-zero absorbance of the 1130–1030 cm −1 feature shown in Figure 1.…”

“…This produced the non-zero absorbance of the 1130–1030 cm −1 feature shown in Figure 1. The resulting alkyl chains were packed in tangled and poorly ordered layers [51]. The surface attachment of QAS thus reached saturation at a QAS concentration below 10%.…”