Self-assembled monolayers formed from alkanethiols on gold in contact with simple fluids and liquid crystals

In the broadest sense, the objective of this work is to extend the level of understanding of the interactions between surfaces and fluids. In particular, we have chosen to study the interactions between a system of well-defined surfaces, Self-Assembled Monolayers (SAMs) formed from alkanethiols on gold, and a type of anisotropic fluids, liquid crystals.; In Part I, we study the wetting properties of isotropic fluids in contact with single component SAMs (SAMs formed from a single alkanethiol). From this study, we conclude that the contact angles of isotropic fluids on single component SAMs are significantly affected by van der Waals forces acting between the isotropic fluid (hexadecane) and the gold underneath of the SAM (through the SAM itself).; In Part II, the anchoring of 5CB is found to be planar regardless of the alkyl chain length used to anchor single component SAMs (n = 3–17) on gold. Our hypothesis that van der Waals forces acting between LCs and the gold underneath of the SAM favor and cause planar anchoring of LCs for all chain lengths lead us to measure the energy associated with the surface-LC interaction, called the anchoring energy. Measurements of the anchoring energy did not measure a value that stayed constant with time. In a related theoretical study, we calculate that flexoelectric forces can not stabilize planar anchoring of LCs perpendicular to the grooves on a grooved substrates (with or without SAMs).; In Part III, we study the anchoring of liquid crystals on mixed SAMs formed from two alkanethiols with different alkyl chain lengths (e.g., CH ₃(CH₂)₉SH and CH₃(CH₂) ₁₅SH) on gold. The anchoring of 5CB on mixed SAMs can be homeotropic on mixed SAMs, and we conclude that interactions between the outer segments of the longer alkyl chains and the LC give rise to the homeotropic anchoring. Further, we observe similar homeotropic anchoring of 5CB on mixed SAMs formed from perfluorinated alkanethiols on gold. Finally, we present a phase diagram for the type of anchoring of 5CB on mixed SAMs formed from different combinations of alkyl chain lengths and different surface compositions of long and short chains.