Toluene-filled polypyrrole microvessels: entrapment and dynamics of encapsulated perylene.

Solid-supported and free-standing polypyrrole microcapsules were synthesized by deposition of the polymer onto toluene droplets. The polymer forms an encapsulating thin layer on the droplet surface. The encapsulation of the solvent was verified by FTIR measurements. Entrapment of other guest molecules can be achieved by using a solution of the guest molecules to prepare the droplets. This was demonstrated with perylene, a hydrophobic fluorescent molecule with well established spectroscopic properties. The encapsulation of perylene was probed with fluorescence spectroscopic techniques and optical microscopy. Time-resolved measurements allowed determination of relaxation dynamics of the fluorophore trapped in the capsules. It was shown that the rotational diffusion of perylene in toluene droplets is best described as a prolate rotor. The reorientation data suggest an increased solvent viscosity within the capsule.