Solution self-assembly of poly(ethylene oxide)-block-poly(furfuryl glycidyl ether)-block-poly(allyl glycidyl ether) based triblock terpolymers: a field-flow fractionation study

Abstract

A well-defined ABC triblock terpolymer, poly(ethylene oxide)-block-poly(furfuryl glycidyl ether)-block-poly(allyl glycidyl ether) (PEO-b-PFGE-b-PAGE), was synthesized via sequential living anionic ring-opening polymerization, and subsequently functionalized by thiol–ene click chemistry. In that way, either a fluorocarbon chain or carboxy groups were introduced into the C segment (PAGE). The self-assembly of the resulting materials in water as selective solvent was studied in detail by asymmetric flow field-flow fractionation (AF4) coupled to multi-angle laser light scattering and dynamic light scattering (DLS). The obtained results were compared with batch DLS and cryogenic transmission electron microscopy (cryo-TEM) results. The influence of the separation conditions on the retention behavior of the triblock terpolymers was evaluated to reveal possible limitations associated with AF4 measurements. The influence of pH value and ionic strength on the solution behavior of the materials, in particular for PEO-b-PFGE-b-PAGECOOH, was investigated as well. Crosslinking of the PAGECOOH by chelating metal ions (Fe3+) was studied under different conditions. In case of PEO-b-PFGE-b-PAGE, spherical micelles of approximately 20 nm (Rh) were observed, whereas the introduction of a fluorocarbon chain led to an increase in size (30 nm, Rh) and the formation of worm-like structures. Carboxy functionalization rendered small (5 nm) disk-like structures. In the latter case, subsequent addition of FeCl3 resulted in the formation of spherical nanostructures ranging from 10 to 60 nm in size, depending on the pH value and the polymer/metal ion ratio.