POS1-0635
Molar mass- and sequence-defined vinyl macromolecules via iterative photoredox decarboxylative addition of α-substituted acrylates
When and Where
Nov 30, -0001
12:00am - 12:00am
Presenter(s)
Dongkyu Kim (Seoul National University)
Co-Author(s)
Abstract
Most synthetic polymers are vinyl polymers synthesized by conventional radical polymerizations using vinyl monomers. Due to the statistical uncertainties, they show a distribution in their molar mass as well as uncontrolled sequences. In contrast, sequence defined vinyl polymers—abbreviated as vinyl sequimers in this study—show precisely defined molecular mass and sequences. Although many previous works1,2 have been done to produce vinyl sequimers, synthesis of vinyl sequimers from simple monomers still remains elusive, because they tend to undergo chain propagation from a radical center. In this work, we report an iterative, light-driven strategy for preparing vinyl sequimers using quantitative addtion of bulky acrylates building blocks. In each cycle, visible-light photoredox decarboxylation generates a carbon-centered radical from a terminal carboxylic acid, which undergoes single addition to a bulky α-substituted acrylate. The resulting α-acyl radical is irreversibly protonated in the photocatalytic cycle without oligomerization, since the steric bulkness of the acrylates suppresses further propagation. The terminal ester can be converted back to a carboxylic acid which can go through quantitative decarboxylative addtion once again. By continuing this iterative cycle, we synthesized various vinyl sequimers including homo-sequimers up to 30 styrene units, and complex sequimers composed of styrene, substituted styrene, and propylene units. Quantitative addition of each building blocks enabled purification of the desired sequimers without chromatographic purification and by simple precipitation.
1. Xu, J. Single unit monomer insertion: a versatile platform for molecular engineering through radical addition reactions and polymerization. Macromolecules 52, 9068–9093 (2019).
2. Lawrence, J. et al. A versatile and scalable strategy to discrete oligomers. J. Am. Chem. Soc. 138, 6306–6310 (2016).
1. Xu, J. Single unit monomer insertion: a versatile platform for molecular engineering through radical addition reactions and polymerization. Macromolecules 52, 9068–9093 (2019).
2. Lawrence, J. et al. A versatile and scalable strategy to discrete oligomers. J. Am. Chem. Soc. 138, 6306–6310 (2016).
