(202b) Stability of the Gyroid Phase in Diblock Copolymers at Strong Segregation

We report high resolution
self-consistent field theory (SCFT) calculations that show the gyroid phase, Q²³⁰,
to be stable in conformationally symmetric linear diblock copolymer melts
prepared within the strong segregation regime,
cN
= 100, over a composition window of ~
1.5%. This window broadens with the
introduction of conformational asymmetry. The SCFT equations were solved using a
novel pseudospectral approach with a plane wave basis and periodic boundary
conditions. Saddle point field configurations were obtained using a
semi-implicit Seidel relaxation algorithm. The modified diffusion equation was
solved using a fourth-order backward differentiation formula and implicit
treatment of the Laplacian operator. Our calculations are consistent with recent
experimental observations of Q²³⁰ in strongly segregated diblocks.