The name is absent

using Picard’s iteration method. For few cases with smaller computational domains,
the iterations start with a step density profile (for segments in A and B blocks) as
the initial guess. However for most of the cases the initial guess is generated by
adding∕removing extra grid points to∕from a previously converged solution. At every
iteration step a new estimate to the density profiles is calculated using eq. 5.10 which
is then mixed with the old density profiles as the new guess for the next iteration. All
the integrations are calculated using the trapezoidal rule. For free energy calculations,
the bulk homogeneous disordered phase is taken to be the reference. Hence all the
free energies, Ω are relative to this state.

5.3 Results and discussion

All the systems considered in this work have a melt like total segment density
of pσ³ = 0.85. The values of e and N are such that the systems are in the strong
segregation limit (SSL) or χ(27V) >> 10 [49]. Bulk (symmetric) diblock copolymer
melts in the SSL are considered first, where the copolymer self assemble into lamellar
structure. Then these copolymers melts are confined between two planar surfaces
to form ultra thin films. The surfaces preferentially attract one of the blocks of the
copolymer. In confinement, the copolymer blocks adjust their lamella to fit into the
confining space and account for the selective adsorption of the blocks at the surfaces.
Due to this we observe various lamellar phases depending upon the thickness of the
film.

123

<<   132   133   134   135   136   137   138   >>

More intriguing information