Synthesis and characterization of specifically fluorinated and structurally tailored self-assembled monolayers on gold.

摘要

Self-assembled monolayers generated from a series of specifically fluorinated SAMs with general formula CH3CF2(CH 2)nSH and a series of cyclopropyl-terminated SAMs were investigated using a variety of surface-sensitive techniques, including ellipsometry, PM-IRRAS, and contact angle goniometry. The presence of a difluoromethylene unit within the film had only a limited impact on the structure of the film. An odd-even effect was apparent in the wettability of these fluorinated SAMs; it was rationalized by extracting structural information from the PM-IRRAS and ellipsometric data. The influence of dipole-dipole as well as dispersive forces is revealed. The structure of the cyclopropyl-terminated SAMs was determined and correlated to small odd-even effects in the wettability of these SAMs. The predominantly sp2 character of the carbon in the methylene group of the cycle is confirmed by contact angle measurements, and a small hydrogen bonding contribution to the contact angle of formamide on these surfaces was discovered.