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]


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.