Growth and organization of (3-Trimethoxysilylpropyl) diethylenetriamine within reactive amino-terminated self-assembled monolayer on silica

TL;DR

This study investigates the formation and organization of amine-terminated self-assembled monolayers using (3-Trimethoxysilylpropyl) diethylenetriamine on silica, highlighting hydrogen bonding effects and optimal conditions for surface functionalization.

Contribution

It provides a comprehensive analysis of DETAS SAM formation, emphasizing hydrogen bonding and process parameters to enhance surface functionalization.

Findings

Hydrogen bonding occurs within the SAM growth process.

Optimal grafting conditions depend on solvent, humidity, and temperature.

DETAS SAMs show well-organized structures suitable for functionalization.

Abstract

Alkane chains are the most commonly used molecules for monolayer fabrication. Long chains are used for their strong van der Waals interactions inducing good layer organization. Amine function-terminated alkyl chains are of great interest and are widely used for further surface functionalization. Since it is mandatory that such layers be organized to provide amine moieties at the surface, the present study deals with exploring amine-terminated SAM formation as an alternative to the usual aminopropylalkylsilane SAM. Additionally, using a long NH2terminated alkyl chain allows the formation of hydrogen bonding thanks to the two NH moieties born along the chain. Furthermore, such hydrogen bonding makes possible to shorten the molecule length while preserving a well-organized monolayer. For this purpose we performed a complete study of the grafting of (3-Trimethoxysilylpropyl) diethylenetriamine (DETAS) on native silicon oxide using various solvents, relative humidity and temperature values. Grafting kinetics was monitored by ellipsometry and goniometry, and SAM structure and organization using AFM and ATR-FTIR spectroscopy. Hydrogen bonding was evidenced within the SAM growth process and in the final complete SAM. We believe such study enables a better control of good quality DETAS SAM in order to improve their efficiency in further surface functionalization applications.