Reusable Catalysts Based on Dendrimers Trapped in Poly(<i>p</i>‐xylylene) Nanotubes

Lindner, Jean‐Pierre; Röben, Caren; Studer, Armido; Stasiak, Michael; Ronge, Ramona; Greiner, Andreas; Wendorff, Hans-Joachim

doi:10.1002/anie.200903448

Cited by 30 publications

(13 citation statements)

References 50 publications

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“…This has been rationalized by considering a simple model of hard spheres in cylindrical tubes where the close-packed configurations have been analyzed and indeed show helical structures [6]. Furthermore, dipolar colloidal particles [7] and thermoresponsive microspheres [5] have been shown to self-organize into chiral aggregates and C 60 molecules [8][9][10] as well as polymers [11][12][13] confined to nanotubes exhibit spirallike structures. Understanding the details of this pattern formation bears a high technological potential as photonic band gap fibers can be formed in cylindrical geometry [14,15] and colloidal nanowires with novel electrical properties may be fabricated out of helical structures.…”

Section: A Letters Journal Exploring the Frontiers Of Physicsmentioning

confidence: 98%

Helicity in cylindrically confined Yukawa systems

Oğuz

Messina

Löwen

2011

EPL

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Section: A Letters Journal Exploring the Frontiers Of Physicsmentioning

confidence: 98%

Helicity in cylindrically confined Yukawa systems

Oğuz

Messina

Löwen

2011

EPL

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“…Additionally, their removal from the reaction mixture and reusability remain major challenges. Porous supports such as membranes, zeolites, carbon nanotubes, and polymer tubes ,,, have been used as supports to facilitate their removal and reusability. However, none of these supports simultaneously provide satisfying results in all terms of catalytic efficiency, catalyst leaching, and reusability.…”

Section: Introductionmentioning

confidence: 99%

Poly(p-xylylene) Nanotubes Decorated with Nonagglomerated Gold Nanoparticles for the Alcoholysis of Dimethylphenylsilane

Kronawitt

Dulle

Schmalz

et al. 2020

ACS Appl. Nano Mater.

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Nanoparticles immobilized on protective polymer supports are highly attractive for various applications in industrial processes. However, nanoparticles tend to agglomerate during the preparation of the polymer supports because of often used harsh conditions and thus lose their specific functionalities, like the catalytic active surface. Here, we report a method that solves the agglomeration and loss of activity by a sacrificial intermediate polylactide (PLA)/gold nanoparticle (AuNP) composite material that was coated with poly(p-xylylene) (PPX) and the selective removal of the PLA resulting in PPX/PLA/AuNP composite mesotube nonwovens with nonagglomerated gold nanoparticles on the inner walls of the polymer tubules. The immobilized AuNP were characterized extensively by electron microscopy and smallangle X-ray scattering (SAXS). With this system, we introduce carriers for nonagglomerated nanoparticles for use in heterogeneous catalysis. The functionality of the composite mesotubes was probed by a model catalytic reaction and compared quantitatively to other nanoparticle-based catalytic systems. The reaction rates, turn over frequencies, Au leaching, permeation of reagents specifically into the tubules, and the reusability were quantified in detail. We report that, in the catalytic model reaction with a gold loading 350 times lower than that of the state-of-the-art composite tubes with agglomerated AuNPs, the composite tubes offer a reaction rate 5 times higher. This system was also validated to work with the catalytic reduction of acetophenone, which is an important industrial reaction for the styrene production. Thus, this system, which shows reusability, stability against common solvents, no agglomeration of AuNPs, and no catalyst leaching, marks major progress toward the translation of high-efficiency nanoparticle catalysis to industrial use and the potential of transfer of other nanoparticle applications like sensoring.

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“…14,15 In materials science, the permanent lodging results in nanoscale filtration devices 16 and reusable catalysts that enclose the dendrimers within nanotubes. 17 Despite these applications, a fundamental understanding of dendrimer behavior under nanoscale confinement is missing. For example, there is currently no definitive answer to the seemingly simple question about a cutoff size for the permeation of dendrimers into pores of given diameter, particularly under the ubiquitous transmembrane voltage present in biological cells as well as in research settings.…”

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confidence: 99%

Dendrimers in Nanoscale Confinement: The Interplay between Conformational Change and Nanopore Entrance

2015

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Hyperbranched dendrimers are nanocarriers for drugs, imaging agents, and catalysts. Their nanoscale confinement is of fundamental interest and occurs when dendrimers with bioactive payload block or pass biological nanochannels or when catalysts are entrapped in inorganic nanoporous support scaffolds. The molecular process of confinement and its effect on dendrimer conformations are, however, poorly understood. Here, we use single-molecule nanopore measurements and molecular dynamics simulations to establish an atomically detailed model of pore dendrimer interactions. We discover and explain that electrophoretic migration of polycationic PAMAM dendrimers into confined space is not dictated by the diameter of the branched molecules but by their size and generation-dependent compressibility. Differences in structural flexibility also rationalize the apparent anomaly that the experimental nanopore current read-out depends in nonlinear fashion on dendrimer size. Nanoscale confinement is inferred to reduce the protonation of the polycationic structures. Our model can likely be expanded to other dendrimers and be applied to improve the analysis of biophysical experiments, rationally design functional materials such as nanoporous filtration devices or nanoscale drug carriers that effectively pass biological pores.

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Reusable Catalysts Based on Dendrimers Trapped in Poly(p‐xylylene) Nanotubes

Cited by 30 publications

References 50 publications

Helicity in cylindrically confined Yukawa systems

Helicity in cylindrically confined Yukawa systems

Poly(p-xylylene) Nanotubes Decorated with Nonagglomerated Gold Nanoparticles for the Alcoholysis of Dimethylphenylsilane

Dendrimers in Nanoscale Confinement: The Interplay between Conformational Change and Nanopore Entrance

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