Binary and mixed brushes for dynamic surfaces

Binary and mixed brushes are comprised of two (or more), chemically distinct polymers randomly grafted to a surface in close proximity. This approach is considered a potent means to manufacture responsive surfaces with tunable physical properties. We highlight recent work in using chemically orthogonal Atom Transfer Radical Polymerization (ATRP) and Radical Addition Fragmentation Transfer polymerization (RAFT) to tailor such mixed surfaces, comprised of chemically disparate polymers covalently grafted to a silica surface. A combination of X-ray photoelectron spectroscopy, synchrotron hard (GISAXS) and soft resonant X-ray techniques (RSoXS), as well as Infrared Atomic Force Microscopy (AFM-IR) was used to provide evidence for responsiveness towards external stimuli. The choice of selective solvents for either of the two species resulted in reversible microphase segregation and can provide a direct pathway towards switchable surface properties.