Stimuli-responsive behavior of micelles prepared from a poly(vinyl alcohol)-block-poly(acrylic acid)-block-poly(4-vinylpyridine) triblock terpolymer

Poggi, Elio [UCL] Guerlain, Claire [UCL] Debuigne, A. [CERM - ULg] Detrembleur, C. [CERM - ULg] Gigmes, D. [Aix-Marseille University (France)] Hoeppener, S. [Jena University (Germany)] Schubert, U.S. [Jena University (Germany)] Fustin, Charles-André [UCL] Gohy, Jean-François [UCL] et al.[show all]

A poly(vinyl alcohol)-block-poly(acrylic acid)-block-poly(4-vinylpyridine) triblock terpolymer (PVOH-b-PAA-b-P4VP) is prepared by hydrolyzing a poly(vinyl acetate)-block-poly(acrylonitrile)-block-poly(4-vinylpyridine) precursor (PVAc-b-PAN-b-P4VP) synthesized by a combination of cobalt-mediated radical polymerization (CMRP) and nitroxide mediated polymerization (NMP). The PVOH-b-PAA-b-P4VP terpolymer is further micellized in water and the accordingly obtained micellar structures are characterized by a combination of dynamic light scattering (DLS) and cryo-transmission electron microscopy (cryo-TEM) as a function of pH. Well-defined micelles are observed in the whole pH range except for pH values below 4.5 where non-aggregated chains (unimers) are present. The formation of micelles can be rationalized by the formation of insoluble PAA/P4VP inter-polyelectrolyte complexes in the 4.5-6 pH range while hydrophobic P4VP cores are observed at pH values above 6. Finally, the effect of the addition of different salts on the micellar characteristic features is investigated.