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

A highly
efficacious photoinduced reversible complexation-mediated
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, Đ < 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.