An AFM Study of the Effects of Silanization Temperature, Hydration, and Annealing on the Nucleation and Aggregation of Condensed OTS Domains on Mica

Abstract

Partial monolayers of octadecyltrichlorosilane (OTS) were formed on mica under different reaction conditions in which the silanization temperature, time, and amount of water adsorbed on the mica substrates were varied. OTS surface coverage increased with silanization time for all samples; however, the amount and distribution of adsorbed OTS varied greatly under these different reaction conditions. AFM analysis showed that OTS formed two phases on mica silanized at 25°C: condensed "island-like" domains and expanded "liquid-like" domains. Partially dehydrated mica silanized at 9°C, however, displayed only condensed domains which were of smaller size compared to those on the 25°C samples. The lateral diffusion and aggregation of small condensed OTS domains to form larger aggregates was evident on all surfaces except the 25°C partially dehydrated mica. A uniform distribution of many small condensed domains surrounded by expanded OTS phases was seen instead. Extended annealing resulted in surface diffusion and aggregation of these domains and nucleation of new condensed domains from the surrounding expanded OTS phases. These observations are consistent with a deposition, diffusion, and aggregation model (DDA) which allows for activated diffusion; however, rigorous modeling is not presented here.

Human Growth Hormone Adsorption Kinetics and Conformation on Self-Assembled Monolayers

“…Alkylsilane (OTS) surfaces were made by immersing the silica slides in a 0.02% (v/v) solution of octadecyltrichlorosilane in dicyclohexyl (Aldrich) for 18 h. After silanization the surfaces were immersed for 30 min in chloroform and rinsed with ethanol and water and dried in a jet of nitrogen gas. The preparation and characterization of the self-assembly process of OTS surfaces is described in more detail by Britt et al 15 Monolayers of ArAc and DPPC were transferred onto OTS-covered silica slides using the Langmuir-Blodgett (LB) technique. In some of the experiments the dyes DiO and DiI were incorporated in the Langmuir layers to monitor the stability of the transferred films during the experiment.…”

Tobacco mosaic virus adsorption on self-assembled and Langmuir–Blodgett monolayers studied by TIRF and SFM

“…Octadecyltrichlorosilane (OTS) and LB films were prepared on fused silica as previously described [12,13]. Silica slides were aminated using N-(2-aminoethyl)(3-aminopropyl)trimethoxysilane (EDA) according to the method of Stenger et al [14] and stored under nitrogen until use.…”

Reactive Molecular Dynamics Simulations of the Silanization of Silica Substrates by Methoxysilanes and Hydroxysilanes

“…Schwartz et al 1 showed the formation of ordered phases of hydrocarbon headgroups densely grafted to mica which followed a fractal growth mechanism. Alkoxysilanes nucleate ordered phases on metal-oxide surfaces, followed by growth through self-assembly from solution to form smooth layers 8 of densely grafted silanes. Despite the widespread application of silanization processes, the underlying chemical mechanisms have not been studied in atomistic detail.…”