Next, we apply the same film deposition and rinse technique to a non-preferential substrate that is known to induce a perpendicular lamellar structure for PS-b-PG(B-r-C) films, a P(S-r-MMA) random copolymer brush. The composition of the random brush that resulted in a non-preferential substrate was found to be 28.8 mol% PS. Figure shows the evolution of the nanostructure of unguided BCP films on the non-preferential brush substrate, 28PS, through two sequential rounds of film application. The top row of Figure , Figure , shows SEM images of the fingerprint pattern, (F1), monolayer upon rinsing (M1) and stained monolayer (M1S) from the first round of film application. The first BCP film, F1, with 𝑡 = 1.75𝐿 " = 34 nm, shows a welldefined lamellar nanostructure, characterized by the isotropic fingerprint pattern. The bright phase corresponds to the PS domain and the dark phase corresponds to the PG(B-r-C) domain.