Comportement de copolymères greffés en milieu solvant sélectif des greffons. Cas des copolymères poly(styrène‐g‐bromure de vinyl‐4 N‐éthylpyridinium)

The dilute solution properties of amphiphilic graft copolymers with an “insoluble” polystyrene backbone (PS) bearing “soluble” poly(4‐vinyl N‐ethylpyridinium bromide) grafts (PVPQ), were studied in water‐methanol‐LiBr (0,1 mol/l) mixtures. In contrast to block copolymers with an identical chemical nature and in the same solvents, graft copolymers do not present intermolecular association. Viscometric data clearly show that a single graft molecule (or “monomolecular pseudo‐micelle”), has a structure similar to that of a “plurimolecular micelle” of a block copolymer, and exhibits a compact star‐like structure.