Amphiphilic Dendrimer-like Copolymers with High Chain Density by Living Anionic Polymerization

We report here a method for the preparation of amphiphilic dendrimer-like copolymers with dendritic polystyrene (PS) core and protonated poly(2-vinyl pyridine) (P2VP) or poly(methacrylic acid) (PMAA) shell. The method employed the efficient coupling reaction of anionic living polymer chains and chlorosilane. The synthesis started from a functionalized 3rd generation dendritic polystyrene, G3PS-g-SiCl, used as the precursor. The dendrimer-like copolymer of styrene and 2-vinyl pyridine, G3PS-g-P2VP, was synthesized by direct coupling of living P2VPLi to the precursor. The dendrimer-like copolymer of styrene and tert-butyl methacrylate, G3PS-g-PtBMA, was synthesized by an indirect procedure in which a living polymer containing mainly PtBMA segment was attached to the precursor. Both methods resulted in the formation of dendrimer-like copolymers with the high molecular weights (up to 8.5 × 106 Da), large molecular sizes (diameter up to 73 nm), and dense shells (number of arms up to 1300). These products, G3PS-g-P2VP and G3PS-g-PtBMA, were protonated with trifluoroacetic acid and acidic hydrolyzed, respectively. After transformation, amphiphilic dendrimer-like copolymers, G3PS-g-P2VPH+ and G3PS-g-PMAA, were obtained. Preliminary results on the solution properties of the amphiphilic products were presented.