Quantitative Structure–Property Relationship Model for Predicting the Propagation Rate Coefficient in Free-Radical Polymerization

In this work, a generalized quantitative structure–property
relationship (QSPR) model is developed for predicting kp by using norm index (NI)-based descriptors,
which is the so-called kp (T, NI)-QSPR model. The as-developed model enables the use of
one unified formula to calculate kp values
for a wide range of monomers, including linear and branched (meth)acrylates,
nitrogen-containing methacrylates, hydroxyl-containing (meth)acrylates,
and so forth. Importantly, the model exhibits excellent performance
when compared with the benchmark kp values
from the literature, and model validation proves the reasonable goodness-of-fit,
robustness, predictivity, and reliability of the as-developed model.
Meanwhile, the Arrhenius parameters show a clear kinetic behavior,
indicating that acrylates have smaller fit, robustness, predictivity,
and reliability of the as-developed model. Meanwhile, the Arrhenius
parameters show a clear kinetic behavior, indicating that acrylates
have smaller Ea values than methacrylates,
which render higher kp values and activities
in free-radical polymerization for acrylates. Notably, the model allows
the prediction of kp values of monomer
mixtures and new monomers. In view of the satisfactory accuracy in
determining kp values, it is expected
that our proposed method will contribute to the determination of kinetic
parameters beyond propagation kinetics for a wide monomer range, and
the obtained Arrhenius parameters can further improve the fundamental
understanding of radical polymerization kinetics.