Understanding and tuning the self-assembly of polyether-based triblock terpolymers in aqueous solution

The synthesis and self-assembly of well-defined poly(ethylene oxide)-block-poly(allyl glycidyl ether)-block-poly(tert-butyl glycidyl ether) (PEO-b-PAGE-b-Pt BGE) triblock terpolymers with varying block lengths of PAGE and PtBGE are reported. The materials were synthesized using sequential living anionic ring-opening polymerization (AROP). The middle block, PAGE, was further modified by post-polymerization addition of 2,3,4,6-tetra-O-acetyl-1-thio- beta -d-galactopyranose viathiol-ene chemistry, resulting in PEO-b-PAGE sub(Gal)-b-PtBGE. Self-assembly of the terpolymers in aqueous media resulted in the predominant formation of core-shell-corona architectures and the aggregates featured a PtBGE core, a PAGE shell, and a PEO corona. The structures were investigated using dynamic light scattering (DLS) and cryogenic transmission electron microscopy (cryo-TEM) measurements. In addition, the presence of a PEO corona rendered the formed micellar structures thermo-responsive, as demonstrated using turbidimetry. Depending on the ratio of hydrophilic to hydrophobic segments and on the thermal history of the samples, several micellar morphologies could be identified, including spheres of different size, worm-like structures, and vesicles. More important, both reversible and irreversible structural rearrangements could be identified during the heating-cooling cycles.