Controlled Growth of Ultra‐Thick Polymer Brushes via Surface‐Initiated Atom Transfer Radical Polymerization with Active Polymers as Initiators

: Polymer brushes exhibit functionalities useful for a large number of applications. Often these functionalities only emerge when the polymer brushes have a desired thickness. Here, a significant breakthrough is achieved in the synthesis of ultra-thick polymer brushes using polymer initiators in the approach of surface-initiated atom transfer radical polymerization, yielding polymer brushes with a controllable thickness up to 15.1 µm. This is reportedly the thickest polymer brush ever synthesized. This approach is applicable for several monomers such as acrylonitrile, methyl acrylate, and styrene, and for other types of polymer substrates such as fibers.