Chain exchange kinetics of polystyrene-block-poly(2-cinnamoylethyl methacrylate) micelles in THF/cyclopentane mixtures

Two to three pyrene groups were attached to the PCEMA block of polystyrene-block-poly-(2-cinnamoylethyl methacrylate) (PS-b-PCEMA) to yield PS-b-PCEMA-Py. Both PS-b-PCEMA and PS-b-PCEMA-Py formed micelles with PCEMA cores and PS shells in THF/cyclopentane (CP) mixtures with sufficiently high CP contents. Mixing such micelles led to chain exchange between different micelles, which increased the pyrene monomer fluorescence intensity at the cost of excimer emission. The data of pyrene monomer fluorescence intensity increase with time and were fitted to a two-exponential-term function. The average lifetime obtained was used to characterize the micelle chain exchange rate. Investigated were the effect of varying solvent composition, temperature, micelle concentration, and the length of both the PS and PCEMA blocks on the chain exchange rate.