THE WETTING BEHAVIOR OF GRAFTED HYDROPHILIC ACRYLIC-MONOMERS

The wetting behavior of vapor phase photografted hydrophilic acrylic m onomers was evaluated by the three most commonly employed techniques, i.e., the captive bubble, the sessile drop, and the Wilhelmy plate tec hnique. The measured contact angles and the overall wetting behavior w ere discussed in light of the non-ideal nature of these surfaces. It w as found that the peculiar nature of hydrophilic grafted surfaces is c arefully reflected in the experimentally measurable contact angles. Wh ile in the case of the captive bubble the hydrophilic and rough nature of these coatings prevent the bubble-surface contact, in the case of the sessile drop the measured contact angles follow the behavior predi cted by contact angle hysteresis theories. Wilhelmy plate measurements , performed as sequential scanning loops, show velocity-dependent effe cts which are linked to the composition, morphology and mobility of th e grafted surfaces.