STUDIES OF STRUCTURE AND LOCAL WETTING PROPERTIES ON HETEROGENEOUS, MICROPATTERNED SOLID-SURFACES BY MICROINTERFEROMETRY

The microstructure and the local wettability of functionalized pattern s is reported. The patterns are formed by the photolithographic struct uring of multilayers of hairy rod polymers on glass/MgF2/SiO2 substrat es. By application of quantitative reflection interference contrast mi croscopy (RICM), the RICM image analysis was improved by accounting fo r (i) multiple reflections and the finite illumination aperture in str atified systems and (ii) geometrical effects in wedge-shaped systems a nd by (iii) optimizing the contrast enhancement through adjustment of the MgF2 coating. The surface free energy of hairy rod films were dete rmined by analysing the contact angle of partially wetting liquid drop lets as a function of the surface tension of the liquid. Periodic latt ices of hydrophobic domains separated by hydrophilic domains were appl ied to check the theory of Joanny and de Gennes [J. Phys. Chem. 81, 55 2-562 (1984)] of contact angle hysteresis at periodic arrays of pinnin g centers. Measurements of the shape of the triple line and the contac t angle hysteresis by RICM confirmed the theoretical predictions. (C) 1997 Academic Press.