Linear-dendritic polymers, self-assembly

Wang et al. reported the self-assembly of organometallic linear-dendritic polymers containing ferrocenyldimethylsilane.357 The linear polymers were prepared via the anionic ringopening of [l]si aferrocenophane, followed by the addition of dendritic chloric poly(benzyl ether). Self-assembly of the polymers was examined in acetone and was reported to occur at concentrations of 0.18 wt %, with a spherical diameter of 50-150 nm. At higher concentrations (0.35 wt %), a bilayer with core spheres formed and at (0.7 wt %) bilayers spheres were formed. 

For polymer chemists it is interesting to know how well-known linear polymers can be linked with dendritic architectures and what the supramolecular consequences of this approach might be. Combination of dendrimers with linear polymers in hybrid linear-dendritic block copolymers has been employed to achieve particular self-assembly effects. Block copolymers with a linear polyethylene oxide block and dendritic polybenzylether block form large micellar structures in solution that depend on the size (i.e., the generation) of the dendritic block [10]. Amphiphilic block copolymers have been prepared by the combination of a linear, apolar polystyrene chain with a polar, hydrophilic poly(propylene imine) dendrimer [11] as well as PEO with Boc-substituted poly-a, -L-lysine dendrimers, respectively [12]. Such block copolymers form large spherical and cylindrical micelles in solution and have been described as superamphi-philes and hydra-amphiphiles , respectively. 

Wood, K.C., Little, S.R., Langer, R., Hammond, P.T. A family of hierarchically self-assembling linear-dendritic hybrid polymers for highly efficient targeted gene delivery. Angew. Chem. 44(41), 6704—6708 (2005). doi 10.1002/Anie.200502152... 

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