Clustering and cooperative dynamics in a reactive system.
We study the dependence of the dynamics on the size of particle clusters that grow by stepwise aggregation in a reactive epoxy-amine mixture. The data reveal the cluster property involved in the glasslike arrest and its quantitative link with the structural relaxation time. We find that the number-average cluster size xn governs the formation of a glassy phase as distinct from a gel phase, and that xn correlates to the size of the "cooperatively rearranging regions" postulated by the Adam-Gibbs model for glass forming liquids. These results suggest that the step polymerization process generates clusters that behave much like dynamical heterogeneities observed in supercooled liquids.
Corezzi
S
S
Dipartimento di Fisica, Università di Roma "La Sapienza", P. le A. Moro 2, I-00185 Roma, Italy.
Fioretto
D
D
Kenny
J M
JM