K. Saalwächter, M. Gottlieb, R. Liu, W. Oppermann.
Gelation as Studied by Proton Multiple-Quantum NMR
Macromolecules 40, 1555–1561 (2007).
A novel NMR approach for the study of gelation in flexible polymer systems is
presented, and the data are compared to results from rheo\-logical and light
scattering experiments. Proton multiple-quantum NMR, also applicable at low
field and amenable to high-throughput experimentation, represents a simple and
robust yet powerful method that allows one to detect the topological gel point,
quantify the gelation kinetics, and characterize composition, microstructure and
dynamics of the forming and the final gel. Applications to end-linked and
statistically crosslinked poly(dimethylsiloxane) chains in the bulk, as well as
statistically crosslinked poly(styrene) chains in solution are presented, and
good agreement as well as complementarity between the results from the different
methods is found.