Polymer brushes––surface immobilized polymers

The synthesis of tethered block copolymer brushes via the use of controlled/‘living’ free radical polymerization techniques presents many significant advantages over traditional free radical polymerization techniques. In our group, we have found that the most versatile controlled/‘living’ free radical polymerization techniques are atom transfer radical polymerization (ATRP) and reversible addition fragmentation transfer (RAFT) polymerization. Both diblock and ABA type triblock copolymer brushes have been synthesized using either ATRP or RAFT. Of particular interest with block copolymer brushes, are their ability to reversibly rearrange upon treatment with selective solvents. This rearrangement of block copolymer brushes can result in the formation of unusual surface morphologies that have been attributed to the formation of either ‘pinned micelles’ or ‘folded’ structures. We have demonstrated that other external stimuli besides block-selective solvents can be used to induce brush reorganization, namely temperature and treatment with supercritical CO2.