Yolk-shell nanoreactors with metal nanoparticle core and ultrathin porous polymer shells are effective catalysts for heterogeneous reactions. Polymer shells provide size-selectivity and improved reusability of catalyst. Nanocapsules with single-nanometer porous shells are prepared by vesicle-templated directed assembly. Metal nanoparticles are formed either by selective initiation in pre-fabricated nanocapsules or simultaneously with the creation of a crosslinked polymer shell. In this study, we investigated the oxidation of benzyl alcohol and benzaldehyde catalyzed by gold nanoparticles and hydrogenation of cyclohexene catalyzed by platinum nanoparticles. Comparison of newly created nanoreactors with commercially available nanoparticles revealed superior reusability and size selectivity in nanoreactors while showing no negative effect on reaction kinetics.
The translational diffusion constants, D, of benzene and a series of alkylbenzenes have been determined in four n-alkanes at room temperature using capillary flow techniques. The alkylbenzenes are toluene, ethylbenzene, 1-phenylpropane, 1-phenylpentane, 1-phenyloctane, 1-phenylundecane, 1-phenyltetradecane, and 1-phenylheptadecane. The n-alkanes are n-nonane, n-decane, n-dodecane, and n-pentadecane. Ratios of the solutes' D values are independent of solvent and in general agreement with the predictions of diffusion models for cylinders and lollipops. For the latter, an alkylbenzene's phenyl ring is the lollipop's candy; the alkyl chain is its handle. A model that considers the solutes to be spheres with volumes determined by the van der Waals increments of their constituent atoms is not in agreement with experiment. The diffusion constants of 1-alkene and n-alkane solutes in n-alkane solvents also are compared with the cylinder model; reasonably good agreement is found. The n-alkanes are relatively extended, and this appears to be the case for the alkyl chains of the 1-alkenes and alkylbenzenes as well.
Hollow polymer nanocapsules with nanometer‐thin porous shells enable the creation of yolk–shell nanoreactors that combine size selectivity, fast reaction rates, and excellent recyclability of the metal nanoparticle catalysts. The image illustrates the advantages of the newly prepared nanoreactors in selective reactions and preservation of catalytic activity compared with commercially available metal nanoparticles on solid support. For more details, see the Full Paper by E. Pinkhassik et al. on
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.