Dynamic Multicompartment-Core Micelles in Aqueous Media

We investigate micellar aggregates of amphiphilic block terpolymers, polybutadiene-block-poly(2-vinyl pyridine)-block-poly(methacrylic acid) (PB(800)P2VP(190)PMAA(550)) and their quaternized analogues polybutadiene-block-poly-(N-methyl-2-vinylpyridinium)-block-poly(methacrylic acid) (PB(800)P2VPq(190)PMAA(550)) in aqueous solution using light scattering (DLS, SLS) and cryogenic transmission electron microscopy (cryo-TEM). At high pH, PB(800)P2VP(190)PMAA(550) forms core-shell-corona micelles with a hydrodynamic radius R(b) similar to 100 nm and a continuous shell of P2VP. However, at pH 4 partial intramicellar interpolyelectrolyte complex (im-IPEC) formation between P2VP and PMAA results in a patchy, collapsed shell. This is far more pronounced for the quaternized analogue, PB(800)P2VPq(190)PMAA(550), which forms aggregates of similar size, also exhibiting a noncontinuous, patchy shell. Here, these im-IPECs of the positively charged P2VPq and the partially negatively charged PMAA are present over the whole investigated pH range (4-10). We further demonstrate that size and charge of the corona can be tuned through the block terpolymer composition, in particular, the ratio between P2VPq and PMAA. These micelles are dynamic and able to react to changes in pH or salinity in terms of corona diameter and aggregation number.