Surface-Initiated Polymerization by Means of Novel, Stable, Non-Ester-Based Radical Initiator

A novel, ester-free initiator for surface-initiated free radical polymerization has been synthesized and tested. The structurally non-symmetrical azo-based initiator features a chemically stable alkane linker between the initiating group and the silane anchoring group, setting it apart from the majority of surface initiators that are linked by hydrolyzable moieties, such as esters. The novel design of the initiator is bolstered by an original synthetic approach, leading to a greater yield and a dramatic reduction in cyanide usage relative to previous methods. Here we demonstrate the capability of this novel initiator for surface-initiated free radical polymerization (SI-FRP), reverse ATRP, and RAFT, noting that Arrhenius behavior of SI-FRP differs significantly from that of FRP in the bulk. Furthermore, we show that polymer brushes formed from the novel initiator are more stable than those formed from ester-based initiators.