PET-RAFT polymerization of star polymers with folded ortho-phenylene cores

Kate G. E. Bradford, Viraj C. Kirinda, Emma A. Gordon, C. Scott Hartley,* and Dominik Konkolewicz*
Macromol. Rapid Commun. 2023, 44, 2300094
[Published version | NSF-PAR | Raw data]

Abstract

ortho-Phenylenes are one of simplest classes of aromatic foldamers, adopting helical geometries because of aromatic stacking interactions. The folding and misfolding of ortho-phenylenes are slow on the NMR timescale at or below room temperature, allowing detection of folding states using ¹H NMR spectroscopy. Here, an ortho-phenylene hexamer was coupled with a RAFT chain transfer agent (CTA) on each repeat unit. A variety of acrylic monomers were polymerized onto the CTA-functionalized ortho-phenylene using PET-RAFT to yield functionalized star polymers with ortho-phenylene cores. The steric bulk of the acrylate monomer units as well as the chain length of each arm of the star polymer was varied. ¹H NMR spectroscopy showed that the folding of the ortho-phenylenes did not vary, providing a robust helical core for star polymer systems.