A poly(glyceryl methacrylate)-block-poly[(2-hydroxyethyl methacrylate)-ran-(2-cinnamoyloxyethyl methacrylate)]-block-poly[(tert-butyl acrylate)-ran-(acrylic acid)-ran-(pyrenemethyl acrylamide)] or PGMA-P(HEMA-CEMA)-P(tBA-AA-Py) sample and a PGAM-PCEMA-P(tBA-AA-Py) sample were synthesized. Spherical micelles were prepared from the triblocks in water with a soluble PGMA corona, an insoluble P(HEMA-CEMA) or PCEMA shell, and an insoluble P(tBA-AA-Py) core. Photocrosslinking the P(HEMA-CEMA) or PCEMA layer yielded nanospheres. Driving I- into the P(tBA-AA-Py) core led to pyrene fluorescence quenching. The decrease in pyrene fluorescence intensity as a function of time after quencher addition was used to examine how the rate of I- diffusion changed with variations in the degree of CEMA crosslinking, in the degree of tBA hydrolysis in the core, and with addition of the plasticizer tetrahydrofuran into water.