Chromophore H-aggregation kinetics of a branched side-chain azo polyelectrolyte

By using spectroscopic variation of azo chromophores in different states as a 'probe', chromophore H-aggregation kinetics of a branched side-chain azo polyelectrolyte PMAPB(6)P-AA in THF/H2O solutions was studied. The THF/H2O ratio showed a significant effect on the H-aggregation rate. The H-aggregation rate increased as the H2O content increased. It indicates that the hydrophobic effect is an important driven force in the process of H-aggregation. The kinetic process of the H-aggregation was characterized by the change of the UV-Vis absorption ratios of the 'isolated' azo chromophores and H-aggregates. Two kinds of kinetic equations were used to fit the H-aggregation process. The process can be well fitted by the second-order kinetic equation.