Self-Assembly of Block Copolymer on Soft Textured Substrate

Soft textured (or sawtooth) surface was used to generate long-range lateral ordering of block copolymer microdomains (BCPs). The replication of the sawtooth pattern on the surface of reconstructed sapphire was accomplished with polymers, like poly(butylene terephthalate) or polyimide. Thin films of BCPs were prepared by spin-coating onto these soft textured substrates and solvent-annealed to develop long-range ordering of BCP microdomains. The surface facets were used to guide the self-assembly of block copolymers over macroscopic distances into a highly ordered array of densely packed cylindrical microdomains oriented normal to the film surface. We found that the amplitude and pitch of the sawtooth patterns could be adjustable by mechanical elongation of soft textured substrates. The lateral ordering of BCP microdomains on textured surface with different amplitude as well as different pitch distance was also investigated.