Abstract
We evaluated the hydrophilicity by measuring the contact angles of model surfaces after their adsorption of dimethyldioctadecylammonium chloride (DMDOAC), a poly (vinyl acetate) emulsion (PVAcE), and their mixture. The adsorbent surfaces used were vacuum-dried organic macromolecular agar gel containing each additive, and hydrophilic glass sheets (glass sheets) and hydrophobic polytetrafluoroethylene sheets (PTFE sheets) with each additive attached. With increasing concentration of each additive, the contact angle of the agar gel (109° without an additive) markedly decreased in a similar hyperbolic manner to about 1/3, resulting in hydrophilization. The contact angle of the hydrophilic glass sheets (33 degrees) showed a maximum value (a 2-fold increase), indicating hydrophobilization, at a low additive concentration, but this angle gradually decreased thereafter with increasing additive concentration. However, the maximum value after adding the mixture was very low, and the change in contact angle was negligible with increasing additive concentration, showing only slight hydrophibilization. The hydrophobic PTFE sheets (120 degrees) showed properties similar to those of agar gel; the contact angle decreased after adding each additive, showing hydrophilization. The degree of hydrophilization after adding the mixture was marked;the contact angle was maintained at slightly more than 20 degrees with increasing additive concentration (about 100 degrees decrease), showing very high hydrophilicity.
