Dongwoo Han

Recently, the equilibration of micelles formed by diblock copolymers has been highlighted due to their applications in various fields; yet, their fragmentation processes are poorly understood. Previous work on the fragmentation kinetics of 1,2-polybutadiene-b-poly(ethylene oxide) (BO), demonstrated that the fragmentation time varies with the total degree of polymerization (Ntotal) as frag ~ Ntotal9/5, which is consistent with the theoretical prediction of Dormidontova, even though that was couched in terms of Ncorona. To clearly resolve the contributions of Ncorona and Ncore to the N dependence, each block length needs to be modified separately. In this study, a series of BO diblocks with fixed NPB (9, 14 kDa) and various NPEO from 6 kDa to 20 kDa, was prepared to examine the corona length effect, and another with nearly constant NPEO (9, 13 kDa) and various NPB from 9 kDa to 14 kDa was prepared to study the core length effect. Micelles are formed by direct dissolution of the BO diblocks in 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl) imide ([C2MIM][TFSI]). The sizes decrease when annealed subsequently at a high temperature (170 ℃). Comparing the fragmentation rates of the series of micelles will establish the individual effects of N¬corona and Ncore. The hydrodynamic radius (Rh) of the micelles will be measured utilizing dynamic light scattering. The Rcore changes will be determined by small-angle X-ray scattering and transmission electron microscopy. We hope to establish the significant determining factors for both Ncore and Ncorona regarding micelle fragmentation kinetics.