ma9b02109_si_001.pdf (12.27 MB)
Universal Scaling Behavior during Network Formation in Controlled Radical Polymerizations
journal contribution
posted on 2019-12-13, 12:33 authored by Joseph
L. Mann, Rachel L. Rossi, Anton A. A. Smith, Eric A. AppelDespite the ubiquity of branched and network polymers
in biological,
electronic, and rheological applications, it remains difficult to
predict the network structure arising from polymerization of vinyl
and multivinyl monomers. While controlled radical polymerization (CRP)
techniques afford modularity and control in the synthesis of (hyper)branched
polymers, a unifying understanding of network formation providing
grounded predictive power is still lacking. A current limitation is
the inability to predict the number and weight average molecular weights
that arise during the synthesis of (hyper)branched polymers using
CRP. This study addresses this literature gap through first building
intuition via a growth boundary analysis on how certain environmental
cues (concentration, monomer choice, and cross-linker choice) affect
the cross-link efficiency during network formation through experimental
gel point measurements. We then demonstrate, through experimental
gel point normalization, universal scaling behavior of molecular weights
in the synthesis of branched polymers corroborated by previous literature
experiments. Moreover, the normalization employed in this analysis
reveals trends in the macroscopic mechanical properties of networks
synthesized using CRP techniques. Gel point normalization employed
in this analysis both enables a polymer chemist to target specific
number and weight average molecular weights of (hyper)branched polymers
using CRP and demonstrates the utility of CRP for gel synthesis.