ANALYSIS OF THE EARLY STAGES OF A CONDENSATION POLYMERIZATION WITH OLIGOMER GPC.

The theoretical treatment of MWD for condensation polymerizations is well established. For simple, linear condensations, such theory predicts a MWD known as the ″most probable″ distribution, based solely on the assumption of equal reactivity of all functional groups. For high mol. wt polymers, the actual MWD arising from such condensations has been investigated directly, by fractionation, and indirectly, by the study of viscosity. For very low mol. wt polymers, or, more specifically, the mixture of low mol. wt oligomers formed during the first stages of condensation, such methods are difficult, if not impossible, to apply. Gel permeation chromatography (GPC), on the other hand, provides a convenient and rapid means for determining the MWD of oligomer mixtures. In reported experiments, the authors have used such a system to study the growth and decay of dimer and trimer concentration in the initial stages of an unusual condensation. For the divinylbenzene-p-cresol condensation, they find good agreement with theoretical predictions for dimer concentration and qualitative agreement for trimer concentration. The use of GPC for observing similar systems is promising.