Stable polymer brushes with effectively varied grafting density synthesized from highly crosslinked random copolymer thin films.

We demonstrate the synthesis of poly(methyl methacrylate) (PMMA) and poly(styrene- b -methyl methacrylate) (P(S- b -MMA)) brushes on crosslinked random copolymer thin films, compositionally varied poly(styrene- r -glycidyl methacrylate) (P(S- r -GMA)), which can be further functionalized with a molecule featuring an initiator group upon crosslinking to form highly stable thin films. With careful optimizations, PMMA brushes were successfully grown from the surfaces of initiator functionalized P(S- r -GMA) via surface-initiated atom transfer radical polymerization. The grafting densities of the PMMA and P(S- b -MMA) brushes were effectively controlled to be in different density regimes by controlling the composition of P(S- r -GMA) and post-crosslinking functionalization methods. Synthesized BCP brushes were stable upon repetitive washing and thermal annealing processes even at high grafting density, highlighting that the outstanding stability of crosslinked P(S- r -GMA) thin films enables close examination of the morphology of thermally annealed P(S- b -MMA) brushes in different grafting density regimes.