We report on the successful encapsulation of hydrophobic substrates into the hydrophobic shell of poly(butadiene)-b-poly(ethylene oxide) vesicles in water and straightforward characterization methods. The hydrophobic fluorescent dye Nile Red was embedded into unilamellar vesicles of PB 130 -b-PEO 66 prepared via different methods leading to different average hydrodynamic radii and distributions but a common hydrophobic shell thickness of ∼16 nm as determined by transmission electron microscopy (TEM). The combination of cryogenic TEM and fluorescence microscopy studies shows that the self-assembled structure remains unchanged when the hydrophobic dye is incorporated within the vesicle shell. Furthermore, highly fluorescent quantum dots with an average diameter of d ) 5.7 ( 0.6 nm as determined by TEM were selected as hydrophobic model substrates and successfully enclosed into the vesicles, as evidenced by fluorescence correlation spectroscopy (FCS) measurements in combination with dynamic light scattering (DLS). Cryogenic TEM imaging reveals the position of the quantum dots, centered inside the double layer of the vesicle shell.

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We show how the viscoelastic properties of membranes formed from poly(butadiene)-blockpoly(ethylene oxide) (PB 130 -b-PEO 66 ) block copolymers can be locally accessed by atomic force microscopy. Polymer membranes are spread on microstructured porous silicon substrates from PB 130 -b-PEO 66 vesicles by decreasing the osmotic pressure of the solution. Local viscoelastic properties of the pore-spanning polymer membranes were obtained from site-specific indentation experiments. Elastic moduli of these membranes were in the order of few MPa, while the elastic moduli of crosslinked membranes considerably increased to few GPa. Furthermore, the energy dissipation and velocity dependence of the hysteresis between indentation and relaxation were quantified and compared with a modified Kelvin-Voigt model. Relaxation times were in the order of hundreds of milliseconds explaining why the stiffness of the membrane increases with increasing indentation velocity.

We present the characterization of different polymeric nanoparticles with asymmetrical flow field-flow fractionation (AF-FFF) in different solvents and additional, independent methods such as static and dynamic light scattering (SLS, DLS) in solution and transmission electron microscopy (TEM) and atomic force microscopy (AFM) for the visualization of the nanoparticles on solid substrates. AF-FFF proves to be a powerful technique to determine average sizes of nanoparticles such as multifunctional polyorganosiloxane nanospheres both, in aqueous dispersion and in organic solvents such as toluene. In addition, dye loaded block copolymer vesicles and cylindrical polyelectrolyte type polymacromonomers are successfully analyzed by AF-FFF and the obtained results are compared to the other techniques used.

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