Free-Standing Films of Semifluorinated Block Copolymer Brushes from Layer-by-Layer Polyelectrolyte Macroinitiators

Free-standing semifluorinated polymer brushes from layer-by-layer (LbL) macroinitiators are demonstrated. LbL deposition of macroinitiators is followed by surface-initiated atom transfer radical polymerization (SI-ATRP). Increasing the number of LbL macroinitiator layers increases grafting density and thickness. The SI-ATRP is conducted by first polymerizing a block of polystyrene followed by the semifluorinated poly-2,2,2-trifluoroethyl methacrylate block. Solvent selective response is investigated by AFM imaging and water contact angle measurements. Specifically, the solvent response of the semifluorinated block copolymer brushes exhibits alternate selectivity to cyclohexane and trifluorotoluene. Solvent responsive free-standing films are also demonstrated.