= Solution
\b[Use a <self-assembled monolayer> of an alkanethiol with a polar terminal group, such as $\mathrm{HS(CH_2)_nOH}$.] Sulfur anchors to <gold> while the exposed hydroxyl groups interact favorably with <water>. A methyl-terminated monolayer would instead present a low-polarity outer surface and usually retain hydrophobic character.
Prepare a clean <gold> surface, allow <adsorption> from a compatible clean solution, and rinse away unbound material. Dense coverage and molecular ordering help make the terminal chemistry reproducible. Mixed chain lengths or incomplete coverage can change the wetting response, so the presence of an OH group in the bottle alone is not sufficient. An original experiment demonstrated hydrophilic hydroxyl-terminated films and showed that mixing chain lengths changed surface order and wettability.<Molecular-Level Control over Surface Order in Self-Assembled Monolayer Films of Thiols on Gold by Colin D. Bain and George M. Whitesides>[Science240, pp.62–63, abstract: sulfur anchoring, exposed hydroxyl groups and effects of mixed chain lengths]{ref}
This specifies the resulting interface rather than treating every freshly prepared <gold> surface as intrinsically identical: contamination, preparation and adsorbates influence the starting <contact angle>.
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