SI-PET-RAFT: Surface-Initiated Photoinduced Electron Transfer-Reversible Addition–Fragmentation Chain Transfer Polymerization

Abstract

In this communication, surface-initiated photoinduced electron transfer-reversible addition–fragmentation chain transfer polymerization (SI-PET-RAFT) is introduced. SI-PET-RAFT affords functionalization of surfaces with spatiotemporal control and provides oxygen tolerance under ambient conditions. All hallmarks of controlled radical polymerization (CRP) are met, affording well-defined polymerization kinetics, and chain end retention to allow subsequent extension of active chain ends to form block copolymers. The modularity and versatility of SI-PET-RAFT is highlighted through significant flexibility with respect to the choice of monomer, light source and wavelength, and photoredox catalyst. The ability to obtain complex patterns in the presence of air is a significant contribution to help pave the way for CRP-based surface functionalization into commercial application.

Surface‐initiated PET‐RAFT polymerization under metal‐free and ambient conditions using enzyme degassing

“…Several attractive features of this approach include low cost, efficient enzymatic activity in the presence of organic solvents, and exceedingly mild polymerization conditions. Extension of this system in combination with Cu‐mediated ATRP to SI‐CRP was recently reported by Zauscher and coworkers, while ATRP and RAFT systems based on select photocatalysts have been used to achieve oxygen tolerance for polymer brush synthesis . Inspired by these studies, we hypothesized that surface‐initiated PET‐RAFT in the presence of GOx would enable efficient polymer brush growth under open‐to‐air environments via a conventional PET‐RAFT mechanism.…”

Designing with Light: Advanced 2D, 3D, and 4D Materials

“…Brush thicknesses ranging from 35 to 170 nm were produced under relatively long exposure times (24–60 h). More recently, Pester and co‐workers implemented a photoinduced electron/energy transfer‐reversible addition‐fragmentation chain transfer (PET‐RAFT) process under visible light for the fabrication of patterned polymer brushes ( Figure ) . The PET‐RAFT process is amenable to a variety of organic and metal‐based catalysts, whose absorptions span the range of the visible spectrum .…”

“…Surface‐initiated photoinduced electron transfer—reversible addition‐fragmentation chain transfer (SI‐PET‐RAFT) polymerization . A) Scheme depicting spatially controlled SI‐PET‐RAFT polymerization from a CTA‐functionalized SiO 2 substrate under visible light irradiation.…”

“…C) Atomic force micrograph of the magenta box in (B) and corresponding line cut. Reproduced with permission . Copyright 2019, American Chemical Society.…”

Comparison of Long‐Term Stability of Initiating Monolayers in Surface‐Initiated Controlled Radical Polymerizations

“…Subsequent controlled polymerization provides defined polymer layer thickness, grafting density, and chemical composition, with the covalent surface-tether making these surfaces robust and chemically resistant. [5] Recently, organic catalysts, [6] external regulation for patterning, [4,[6][7][8][9][10][11][12][13][14] and increased oxygen tolerance [6,9,13,15,16] have been introduced to allow complex patterning on the benchtop. These improvements now offer more intriguing possibilities for engineering of layered and patterned polymer thin films than ever before.…”