The name is absent

z∕σ

Figure 5.11: Anti-symmetric segment density profiles of the A block (solid black curve)
and B block (dashed black curve) of the copolymer for (a) H = 14σ, and (b) H = 16.4σ.
For the diblock copolymer, N = 8 and e∕kT = 0.289. For surfaces, e_w∕kT = 0.3.

number of segments. These diblock copolymers are then confined between two paral-
lel surfaces, where the surfaces selectively prefer one of the blocks of the copolymer,
to form ultra-thin copolymer films. These films show two types of parallel lamel-
lar phases. In symmetric lamellar phases, the preferred block is present at the two
surfaces and in anti-symmetric lamellar phases one of the surfaces is covered with
the energetically unfavorable block. For comparatively weaker surface preference, the
symmetric lamellar phases are stable near integer values of the effective film thick-
ness (H_ejγ), when the lamellar period is in accord with ŋð. The anti-symmetric
lamellar phases are stable only at smaller film thickness near half-integer values of
H_e∕y. However, only symmetric lamellar phases are found to be stable when the sur-

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