Gold nanoparticle monolayer formation using imine reaction

Abstract

The formation of high-coverage, stable gold nanoparticle (AuNP) monolayers on silicon substrates was investigated using imine reactions as a modal covalent reaction. This study aimed to optimize reaction parameters, evaluate solvent stability, and explore the scalability of the deposition process for practical applications. AuNPs functionalized with aldehyde groups were covalently bonded to amine-functionalized silicon wafers via imine linkages, ensuring strong and stable monolayer attachment. Systematic optimization identified the optimal conditions as a triethylamine (TEA) concentration of 1 mM, AuNP concentration of 0.35% (w/v), and reaction time of 5 hours. These conditions achieved a monolayer coverage of 88%, as confirmed by scanning electron microscopy (SEM). Excess TEA concentrations and prolonged reaction times led to reduced coverage due to aggregation and multilayer formation. Solvent studies demonstrated remarkable stability of the monolayers in ethanol, toluene, and DMF, with no degradation observed after 12 hours of immersion. This work contributes to advancing nanomaterial assembly techniques by providing a reliable strategy for fabricating uniform, stable AuNP monolayers, paving the way for their integration into cutting-edge technologies.