Divergent Synthesis of Graft and Branched Copolymers through Spatially Controlled Photopolymerization in Flow Reactors

Abstract

In this work, we demonstrate the controlled synthesis of graft and branched copolymers using one-pot (batch) or one-pass (flow) processes without intermediate purification. The formation of poly(methacrylate) copolymers with pendent reversible addition–fragmentation chain transfer (RAFT) agent functionalities was performed using a selective photoactivation approach in the first step, specifically via green light-mediated direct photoRAFT polymerization. A nonselective photoinduced chain extension using red light-triggered photoinduced energy/electron transfer (PET)-RAFT polymerization was then performed to provide tailored graft copolymers. Notably, the application of this protocol to a flow process with two spatially segregated unit operations provides a route to independent control of the backbone-forming step (unit operation one) and the subsequent chain extensions (unit operation two). By alternating the light sources in both unit operations between the On and Off states, a range of macromolecular architectures could be prepared from the same starting materials. To demonstrate the power of this divergent approach, a series of graft copolymers with tailored backbone lengths and number and molecular weight characteristics of side chains were synthesized using the same starting materials by a single pass process. Additionally, the polymer architecture was switched between graft and hyperbranched architectures via external manipulation of light sources.

ICB Affiliated Authors

Authors
Nathaniel Corrigan, Francisco J. Trujillo, Jiangtao Xu, Graeme Moad, Craig J. Hawker, and Cyrille Boyer
Date
Type
Peer-Reviewed Article
Journal
Macromolecules
Volume
54
Number
7
Pages
3430–3446
Emblems