Controlled Polymer-Brush Growth from Microliter Volumes using Sacrificial-Anode Atom-Transfer Radical Polymerization

摘要

Polymer brushes (i.e. polymer chains covalently tethered to the substrate at one end) have emerged as one of most useful and versatile routes to chemically functionalize substrates. Polymer brushes have been widely investigated to create surface coatings with tunable wettability and anti-biofoul-ing, for protein immobilization, applications including filtration and actuation, and many other studies into the nanoscale properties of (patterned) polymer brushes. Typically, brushes form planar films, but locally changing the initiator grafting density using e-beam or dip-pen nano-displacement lithography, leads to polymer films with gradients in thickness after polymerization. In addition to the formation of gradients, another major experimental challenge in the growth of polymer brushes is the extremely poor efficiency, in terms of monomer usage. Typically, milliliters of monomer solution are used to grow brush films in the range of (hundreds of) nanometers. This, combined with the requirement to grow brushes under controlled conditions, limits the use of precious monomers, as well as potential industrial applications.