Polymerization of Semi-Fluorinated Alkane Thiol Self-Assembled Monolayers Containing Diacetylene Units

We report the formation and subsequent topochemical polymerization of semi-fluorinated self-assembled monolayers (SAMs) containing diacetylene groups. The SAMs used were formed via the adsorption of the following derivatives:  CF₃(CF₂)_n(CH₂)₁₆C⋮CC⋮C(CH₂)₁₀SH (n = 2, 3) and CF₃(CF₂)_n(CH₂)₁₁C⋮CC⋮C(CH₂)₁₀SH (n = 9, 12) onto the surface of gold. The polymerization of the monolayers was initiated by UV irradiation and was monitored using resonance Raman spectroscopy. SAMs with short semi-fluorinated portions were found to polymerize more effectively than those with longer portions, indicating that steric factors become important with increasing perfluorinated chain length.