MICELLIZATION OF MODEL GRAFT-COPOLYMERS IN DILUTE-SOLUTION

The micellization behaviors of graft copolymers consisting of polystyr ene, PSt, backbones and poly(tert-butyl methacrylate), PtBuMA, or poly (methacrylic acid), PMAA, branches were studied in dilute solutions by low angle laser light scattering, LALLS, viscometry, and dynamic ligh t scattering, DLS. tert-Amyl alcohol, a selective solvent for the PtBu MA branches, and tetrahydrofuran, THF, a selective solvent for the PSt backbones, were used to promote the formation of micelles from the PS t-g-PtBuMA and PSt-g-PMAA graft copolymers, respectively. Low aggregat ion numbers were obtained in all cases due to the specific architectur al characteristics of the samples. Aggregation numbers were dependent on the type of the component (backbone or branches) that was insoluble in the selective solvent. The formation of micelles from the PSt-g-Pt BuMA graft copolymers in tert-amyl alcohol is evidenced by the appeara nce of large and rather loose aggregates at a certain concentration ra nge. This kind of behavior was not observed for the micelles formed fr om the graft copolymers with PMAA branches in THF. Stable and compact structures were obtained in this case, with their hydrodynamic behavio r resembling that of hard spheres.