as
X = ∕*[⅛)+4W - 2≤(r)J, (5.3)
where к is the Boltzmann constant and T is the temperature. The repulsions between
these segments are treated as hard sphere repulsion with temperature and density
independent hard sphere diameter (σ).
For copolymer ultrathin films, the copolymer is confined between two smooth
planar surfaces separated by H. The surfaces are located at z = O and z = H, where
z is the direction normal to the surfaces. The total external field on a segment ‘ct’ of
the copolymer due to these surfaces is given as
V*xt(z) = Vwa(z) + Vwa(H - z), (5.4)
where the first contribution is from the surface at z = O and the second from the
surface at z = H. The surface-segment interactions are modeled by a 9-3 LJ potential.
K,α(*) = < V^zmin)-v^{zc) if⅛-
— Zmin
(5.5)
^wa (^) ^wa (zc) ɪf Zmin < Z < Zc
where zmin = (2∕5)1∕6σu,α is the position of potential minima, zc — ,iσwa is the
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