Cryogenic transmission electron microscopy (cryo-TEM) micrographs showing changes in micelle core radii between Day 0 (a) and Day 10 or Day 11 (b) for several polymer concentrations. The initial polymer concentrations were 2 mg ml−1, 5 mg ml−1 and 10 mg ml−1. After dialysis, the concentrations followed the same trend but were approximately half of the initial concentrations. In each case, the THF content was 43% by volume before dialysis into water. Scale bar, 100 nm. (c) Small angle neutron scattering (SANS) data (points) and fits (solid lines) for micelle solutions at different concentrations. (d) Corresponding number frequency distribution of core radii from fits to SANS data. Samples for the SANS experiments were prepared in 43% by volume THF and dialyzed against D2O, and SANS experiments were performed at Day 11 post-dialysis to D2O. The relative percentages of the smaller (Rc <8 nm) and larger (Rc ⩾8 nm) core radii populations are shown on the frequency curves. The sensitivity of the number frequencies from the SANS data modelling was approximately ±5% for the 2 mg ml−1 data and ±15% for the 5 mg ml−1 and 10 mg ml−1 data.