We describe a versatile method to obtain functional hollow nanoreactors with a hydrophilic liquid core. The synthesis of hollow polyurea, polythiourea, and polyurethane nanocapsules was performed by interfacial polycondensation or cross-linking reactions in inverse miniemulsion. The miniemulsions were built upon emulsification of a solution of amines or alcohols in a polar solvent with cyclohexane as the nonpolar continuous phase. The addition of suitable hydrophobic diisocyanate or diisothiocyanate monomers to the continuous phase allows the polycondensation or the cross-linking reactions to occur at the interface of the droplets. The wall thickness of the capsules can be directly tuned by the quantity of the reactants. The nature of the monomers and the continuous phase are the critical factors for the formation of the hollow capsules, which is explained by the interfacial properties of the system. The resulting polymer nanocapsules could be subsequently dispersed in water. The capsules were found to be spherical when formamide was used as the liquid core, whereas elongated capsules were obtained with water. Finally, we used these hollow nanoreactors as a model system for the preparation of silver nanoparticles by reducing silver nitrate solutions encapsulated by the polyurea shell. These syntheses are the first that allow the encapsulation of hydrophilic compounds in miniemulsion in a hollow structure.

No abstract

No abstract

ZUSAMMENFASSUNG:Durch Reaktion von vernetzten und unvernetzten Copolymeren aus p-Lithiumstyrol und Styrol mit Benzonitril und nachfolgende Umsetzung mit Methanol wurden polymere (Phenyl-4-vinylpheny1)methanimine (5) erhalten, die auf verschiedenen Wegen am Stickstoffatom bromiert wurden. Mit den so hergestellten polymeren N-Brom-(phenyl-4-vinylphenyl)methaniminen (7)lieoen sich geeignete monomere Substrate in der Seitenkette und in Allylstellung bromieren. Die auf diese Weise entbromierten makromolekularen Substanzen konnten durch erneute Bromierung am Stickstoffatom regeneriert werden. SUMMARY:Polymeric (phenyl-4-vinylpheny1)methanimines (5) were obtained by reaction of crosslinked and also of linear copolymers from p-lithiumstyrene and styrene, with benzonitrile and subsequent treatment with methanol. They could be brominated at the nitrogen-atom in different ways. With the resulting polymeric N-bromo(pheny1-4-vinylpheny1)methanimines (7) suitable monomeric substrates could be brominated in aromatic side chains and in allylic position. The resulting debrominated polymers could be regenerated by repeated bromination at the nitrogen atom. Einleitung

Several copolymers of 4(5)-vinylimidazole (1 a) containing different amounts of divinylbenzene (DVB) as crosslinking agent and also copolymers of l a (crosslinked, 4 mol-Yo) with styrene, 4-vinylpyridine, 1-vinylimidazole, or Cvinylbenzoic acid were obtained by radical polymerisation. The pendant imidazole-groups of all of these polymers could be acylated in their I-position. The swellability of the resulting polymeric N-acylated imidazoles in suitable solvents was investigated. They were used for the acylation of amines and alcohols, variing the mole ratio reactive polymer/substrate, the reaction time, and the solvent. A gradual reactivity was found for the reaction with low molecular mass compounds according to the nucleophilicity of the substrates. Ethanolamine could be selectively N-acetylated and in the case of the mono-trifluoroacetylation of hexamethylenediamine significantly high yields of mono-acylated product were obtained. After the reaction the polymers could be regenerated without any loss of activity.

No abstract

not Available.

mas in applied-B ion diodes. We have performed experiments with electrode conditioning and cleaning techniques including RF discharges, anode heating, cryogenic cathode cooling and anode surface coatings that have been successful in mitigating some of the effects of electrode contamination on ion diode performance on both the SABRE and PBFA accelerators.'We are developing sophisticated spectroscopic diagnostic techniques that allow us to measure the electric and magnetic fields in the A-K gap, we compare these measured fields with those predicted by our 3-D particle-in-cell (PIC) simulations of ion diodes, and we measure anode and cathode plasma densities and expansion velocities. We are continuing to develop E-M simulation codes with fluid-PIC hybrid models for dense plasmas, in order to understand the role of electrode plasmas in ion diode performance. Our strategy for improving high power ion diode performance is to employ and expand our capabilities in measuring and modeling A-K gap plasmas and leverage our increased knowledge into an increase in total ion beam brightness to High Yield Facility (HYF) levels.We describe measurements, modeling, and mitigation experiments on the effects of anode and cathode plas-