LAUSR

The effect of micellar size on the chain exchange kinetics in spherical micelles consisting of poly(methyl methacrylate)-block-poly(n-butyl methacrylate) (PMMA-b-PnBMA) in a mixture of ionic liquids (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][TFSI], and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [BMIM][TFSI]) was investigated using time-resolved small-angle neutron scattering (TR-SANS). Two spherical micelles with different core sizes were prepared from a single block copolymer by using different protocols. In one case the micelles were formed in the presence of a cosolvent, while in the other a polymer thin film was directly dissolved in the ionic liquid. Interestingly, the micelle core size prepared from the latter method is ∼30% larger than that obtained in the former case. TR-SANS experiments reveal that the rate of single chain exchange in the micelles with a larger core size is slowed down by ∼3 times compared to the smaller core radius. This can be pos...