Radical ring-opening polymerization (RROP) of cyclic monomers, such as functionalized vinylcyclopropanes (VCPs), produces polymers with low volume shrinkage, or even volume expansion, which has vast application potentials in modeling and filling materials. VCPs generally polymerize through two mechanistic pathways in RROP, affording polymers with mixed linear and cyclobutane units. Historical RROP of VCPs is often performed at elevated temperatures and suffers from several limitations. For example, the free radical polymerization of VCPs is uncontrolled while the Cu(I)-catalyzed ring-opening atom transfer radical polymerization (ATRP) of VCPs provides excellent control over the chain growth, however, it only reaches low conversion. Organocatalyzed atom transfer radical polymerization (O-ATRP) through photoredox catalysis has obtained increasing attention. By using N,N-2-naphthyl dihydrophenazine as the photocatalyst, we achieved the first visible-light-regulated ring-opening ATRP of VCPs under mild conditions. A variety of functionalized vinylcyclopropanes were tolerated to afford polymers in high conversions (typically &gt; 90%), and with predictable molecular weight, low dipersities (1.12 – 1.23), and a high degree of linear composition (&gt; 90%). Properties of these obtained polymers, such as high thermal stability and tunable glass transition temperature (Tg), may inspire future applications in material science.

Organocatalyzed ring-opening atom transfer radical polymerization of vinylcyclopropanes driven by visible light

256th National Meeting (2018)

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