Langmuir isotherms of flexible, covalently crosslinked gold nanoparticle networks: Increased collapse pressures of membrane-like structures

Abstract

A series of hydrophobic gold nanoparticles were prepared by the Brust–Schiffrin method, employing thiols with chain lengths ranging from C6-C18 as capping ligands. Solutions of the purified nanoparticles were cast as monolayers upon the air–water interface of a Langmuir trough. After collecting characteristic compression isotherms and noting collapse pressures for each monolayer film at 20°C, the impact of covalent crosslinking was studied by introducing a solution of dodecanedithiol in hexanes to the floating film of nanoparticles. It was discovered that characteristic collapse pressures increased significantly for films of nanoparticles with capping ligand alkyl chain lengths of less than 16 carbons. The films were easily transferred to a substrate, and TEM analysis revealed that the films retained a flexible, membrane-like morphology.