Kinetics of autophobic dewetting of polymer films

We experimentally investigated the retraction of poly(dimethylsiloxane) fil ms of variable thickness on layers of chemically identical molecules, end-g rafted onto a silicon substrate (autophobic dewetting of a melt-on-brush sy stem). Measuring simultaneously the dewetted distance (d) and the width (tu ) of the rim formed by the collection of the retracted liquid, we were able to determine in situ and in real time (t) the contact angle, the velocity of retraction, and the energy dissipation mechanism at the melt-brush inter face. The dewetting velocity decreased linearly with the width of the rim. Together with the characteristic thickness dependence and an exponent alpha of 2/3 for the power-law behavior of d similar to t(alpha), we concluded t hat the melt is slipping on the brush. The slippage length was on the order of 10 mu m, indicating little interpretation between melt and brush. We de monstrate that dewetting experiments represent a valuable tool for the char acterization of static and kinetic properties of polymer-polymer interfaces .