The kinetics of aggregation and disaggregation in the systems that form liquid crystals has not been explored. New measurements reveal that the characteristic time can range from a millisecond to many hours. In the IR-806 system, the aggregation kinetics follow a stretched exponential function almost perfectly, probably resulting from a wide range of aggregate sizes, each with a slightly different characteristic time.
300
250
Absorbance Coefficient (mm-1 wt%-1)
Some dye molecules in solution naturally aggregate, and if the aggregates are anisotropic and concentrated, they order into a liquid crystal phase. In one such dye, IR-806, different states of aggregation have different absorption peaks. At low concentration the monomer peak dominates. At a higher concentration the dimer or small aggregate peak is the largest. Finally, at an even higher concentration the peak due to large aggregates is present. A simple theory in which dimer formation is characterized by a larger equilibrium constant than larger aggregates is consistent with the data.
Monomer
200
Large Aggregate 150
Dimer/Small Aggregate
100
50
0 0
0.2
0.4
0.6
Concentration (wt%)
0.8
1
