Chapter 8: Structure–Property Relations in Semifluorinated Polymethacrylates

Poly(methacrylate)s with semifluorinated side-chains of the general structure –(CH₂)_n–(CF₂)_m–F were studied to elucidate the influence of the side-chain structure on the ordering behavior in the solid state and in thin films. The aim was to find correlations between the chemical structure of the polymer, chemical composition near the surface, order in the thin films and wetting behavior. The polymers were synthesized by radical polymerization, carefully purified and prepared as thin films by spin coating. Even with comparably short semifluorinated side-chains, –(CH₂)₂–(CF₂)₆–F, a weakly ordered structure was found both in bulk and in thin films. A pronounced layered structure was proved in polymers with longer side-chains, –(CH₂)₂–(CF₂)₈–F and –(CH₂)₁₀–(CF₂)₁₀–F, both in bulk by SAXS and WAXS and in thin films by XRR and GISAXS. Linear correlations between advancing and receding contact angle and number of C atoms in the side-chains, and between surface composition measured by XPS and solid surface tensions obtained from water contact angles with the equation of state approach, could be demonstrated. This offers the opportunity for tailor-made coatings.