Phase behavior of symmetric ternary block copolymer-homopolymer blends in thin films and on chemically patterned surfaces

The phase diagram of symmetric ternary blends of diblock copolymers and homopolymers in thin films was determined as a function of increasing volume fraction of homopolymer (phi(H)) and was similar to that for these materials in the bulk. Blends with compositions in the lamellar region of the diagram (phi(H)<= 0.4) could be directed to assemble into ordered lamellar arrays on chemically striped surfaces if the characteristic blend dimension (L-B) and the period of the stripes (L-S) were commensurate such that L-S=L-B +/- 0.10L(B). Blends with compositions in the microemulsion region of the diagram (phi(H)approximate to 0.6) assembled into defect-free lamellar phases on patterned surfaces with L-S >= L-B, but formed coexisting lamellar (with period L-S) and homopolymer-rich phases when L-S < L-B.