Collapse of polymer brushes grafted onto planar ... - Wageningen UR
Collapse of polymer brushes grafted onto planar ... - Wageningen UR
Collapse of polymer brushes grafted onto planar ... - Wageningen UR
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FIRST-ORDER WETTING TRANSITION AT FINITE CONTACT ANGLE<br />
F.A.M. Leermakers, J. Maas and M.A. Cohen Stuart<br />
Laboratory <strong>of</strong> Physical Chemistry and Colloid Science, <strong>Wageningen</strong> University,<br />
Dreijenplein 6, 6703 HB <strong>Wageningen</strong>, The Netherlands<br />
email: frans@fenk.wau.nl<br />
ABSTRACT<br />
The wetting <strong>of</strong> a <strong>polymer</strong> brush by a melt <strong>of</strong> similar chains can have a window <strong>of</strong> complete wetting. In this<br />
case there is a classical allophobic wetting transition, at low grafting density σ , and an autophobic one at<br />
high σ . However, when the melt chains are much longer than the brush chains, the contact angle α goes<br />
through a non-zero minimum where ∂α ∂σ<br />
/ has a jump. An SCF analysis and experimental observations<br />
indicate a double-well disjoining pressure curve, consistent with a novel first-order wetting transition at finite<br />
α . The meta-stable contact angle can become zero. This is important information in order to understand the<br />
kinetics <strong>of</strong> dewetting. The results show that the classical wetting theory must be extended in order to account<br />
for incomplete wetting (i.e. wetting transitions at finite contact angle).
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