Hydrogen Bond Effects: A Strategy for Improving Controllability in Organocatalytic Photoinduced Controlled Radical Polymerization Targeting High Molecular Weight

A highly efficacious photoinduced reversible complexationmediated polymerization (photo-RCMP) system using amino alcohol N-oxide as the catalyst has been developed, allowing access to controlled high-molecular weight polymers of different methacrylates (Mn = 497-815 kg/mol, D < 1.5), which is very challenging for those known catalytic systems of photo-RCMPs and most organocatalytic photoinduced controlled radical polymerization as it demands higher controllability of catalysts. The monomers can be converted into the polymers nearly quantitatively under simulated or natural sunlight irradiation. Strong hydrogen bond effects are observed in this high-molecular weight photo-RCMP, in terms of both monomer conversion and molecular weight controllability. The insights of the effects are revealed as the intramolecular hydrogen bond of the N-oxide catalyst modifies the electron density of N-oxide, and thereby facilitates the regeneration of the catalyst (activator) and release of I2 as a predominant effective regulator of radical concentration, by the studies of X-ray analysis, control experiments, density functional theory calculation, ultraviolet-vis absorption spectroscopy, etc.

Automated summary

A highly efficacious photoinduced reversible complexationmediated polymerization system has been developed using amino alcohol N-oxide as the catalyst, allowing access to controlled high-molecular weight polymers of different methacrylates. The research shows that strong hydrogen bond effects play important roles in both monomer conversion and molecular weight controllability.