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 polysty rene-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 suffi ciently high CP contents. Mixing such micelles led to chain exchange b etween different micelles, which increased the pyrene monomer fluoresc ence intensity at the cost of excimer emission. The data of pyrene mon omer fluorescence intensity increase with time and were fitted to a tw o-exponential-term function. The average lifetime obtained was used to characterize the micelle chain exchange rate. Investigated were the e ffect of varying solvent composition, temperature, micelle concentrati on, and the length of both the PS and PCEMA blocks on the chain exchan ge rate.