The name is absent

e_wβ∕kT = —5, while the segment-segment interactions are the same as in figures 4.6a
and b. The theoretical density profiles for both the segment types closely agree with
the results from molecular simulation as shown in figure 4.7a. The structure is mainly
governed by the two surfaces. The density of “A” segment is very high near the surface
and there are essentially no “B” segments near the surface.

Now consider the case of a long symmetric diblock copolymer with 50 segments
(25A25B) confined in the same pore with weakly selective walls. The segment-segment
and segment-surface interactions are same as in figures 4.6a and b. The density
profiles of both “A” and “B” obtained from the theory are shown in figure 4.7b.
The results are similar to the results obtained by Cao and Wu [112] using their
density functional theory. The long copolymer has to fit into the smaller confined
space by adjusting its configurations. Hence lamellae of “A” and “B” are formed
which are parallel to the two surfaces. In this case, two lamellae of “A” and “B” are
formed. One of the lamellae of “A” is in the middle while two half lamellae of “A”
are near the two surfaces. The two lamellae of “B” lie between the “A” lamellae. The
period of the lamellae and thereby number of lamellae depend upon their equilibrium
lamellar period, Lq in the bulk system. Even in the absence of two surfaces these
diblock copolymers self assemble into parallel lamella with the equilibrium period
Lo depending upon the interactions between the two distinct polymer blocks. A
detailed study of the effect of confinement on this equilibrium period and thereby
the microstructure of these diblock copolymers is the subject of chapter 5 of this

107

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