Using automatic, continuous online monitoring of polymerization reactions (ACOMP) the
final, divergent growth phase (FDGP) of the condensation polymerization of dimethylamine, epichlorohydrin,
and ethylenediamine was monitored, which produced a highly ramified, polyelectrolytic polyamine.
The weight average mass, Mw, increased exponentially during the FDGP, whereas weight averaged
intrinsic viscosity [è]w increased slowly, reaching a plateau. Multi-detector gel permeation chromatography
(GPC) revealed that polymers of mass 20 000 to 106 are branched and self-similar, but above this mass,
[è] increases less strongly with M. This appears to be due to higher order ramification, a precursor to
gelation. The ACOMP trends in Mw and [è]w provide direct online evidence of this process. It is shown
computationally that a mere increase in polydispersity cannot explain this behavior. GPC showed the
mass distribution becomes highly asymmetric as conversion increases. A plausible kinetic model for the
distribution asymmetry is introduced, and a complementary model for the effects of higher order
ramification on [è]w.
