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Surface-modified carbon nanotubes (CNTs) have become well-established filler materials for polymer nanocomposites. However, in immiscible polymer blends, the CNT-coating is selective toward the more compatible phase, which suppresses their homogeneous distribution and limits harnessing the full potential of the filler. In this study, we show that multiwalled CNTs with a patchy polystyrene/poly(methyl methacrylate) (PS/PMMA) corona disperse equally well in both phases of an incompatible PS/PMMA polymer blend. Unlike polymer-grafted CNTs with a uniform corona, the patchy CNTs are able to adjust their corona structure to the blend phases by selective swelling/collapse of respective miscible/immiscible surface patches. Importantly, the high interfacial activity of patchy CNTs further causes a significant decrease in PMMA droplet size with increasing filler content. The combined effect of compatibilization and homogeneous distribution makes patchy CNTs interesting materials for polymer blend nanocomposites, where next to the compatibilization, a homogeneous filler distribution is important to gain the desired materials property (e.g., reinforcement).

In this work, we provide a detailed study on the influence of patch size and chemistry on the catalytic activity of patchy hybrid nonwovens in the gold nanoparticle (Au NP) catalysed alcoholysis of dimethylphenylsilane in n-butanol. The nonwovens were produced by coaxial electrospinning, employing a polystyrene solution as the core and a dispersion of spherical or worm-like patchy micelles with functional, amino group-bearing patches (dimethyl and diisopropyl amino groups as anchor groups for Au NP) as the shell. Subsequent loading by dipping into a dispersion of preformed Au NPs yields the patchy hybrid nonwovens. In terms of NP stabilization, i.e., preventing agglomeration, worm-like micelles with poly(N,N-dimethylaminoethyl methacrylamide) (PDMA) patches are most efficient. Kinetic studies employing an extended 1(st) order kinetics model, which includes the observed induction periods, revealed a strong dependence on the accessibility of the Au NPs' surface to the reactants. The accessibility is controlled by the swellability of the functional patches in n-butanol, which depends on both patch chemistry and size. As a result, significantly longer induction (t(ind)) and reaction (t(R)) times were observed for the 1(st) catalysis cycles in comparison to the 10(th) cycles and nonwovens with more polar PDMA patches show a significantly lower t(R) in the 1(st) catalysis cycle. Thus, the unique patchy surface structure allows tailoring the properties of this "tea-bag"-like catalyst system in terms of NP stabilization and catalytic performance, which resulted in a significant reduction of t(R) to about 4 h for an optimized system.

Zinc oxide (ZnO) nanoparticles were mesostructured by polybutadiene-block-poly(2-vinylpyridine) cylindrical polymer brushes as a template. Loading the positively charged vinylpyridine block with ZnO nanoparticles produced hybrid rods with high aspect ratio. Mesostructured ZnO nanotubes obtained by pyrolytic template removal show high activity in the photocatalytic degradation of ciprofloxacin using a continuous flow reactor and irradiation with terrestrial solar spectrum. In comparison with Degussa P25, a titanium dioxide photocatalyst, the degradation is 2.9 times faster. Due to its non-woven microstructure, the photocatalyst, moreover, can be easily separated from fluid reaction media by filtration.

Die heterogene Katalyse an tragerfixierten Nanopartikeln (NP) ist ein uberaus attraktives Forschungsfeld. Eine der grosten Herausforderungen ist jedoch weiterhin die effiziente Stabilisierung der NP ohne Einschrankung ihrer katalytischen Aktivitat. Durch eine Kombination bekannter Top-down- (koaxiales Elektrospinnen) und Bottom-up-Methoden (kristallisationsinduzierte Selbstassemblierung) ist es uns gelungen, Fasermatten mit funktionellen, nanometergrosen Kompartimenten (Patches) auf der Oberflache herzustellen. Diese Patches sind in der Lage, Gold-Nanopartikel (AuNP) selektiv zu binden und zu stabilisieren. Die mit AuNP beladenen Hybridfasermatten zeigten in der Alkoholyse von Dimethylphenylsilan bereits nach vergleichsweise kurzen Reaktionszeiten sowie unter milden Bedingungen quantitativen Umsatz. Die exzellente Wiederverwendbarkeit zeigt sich darin, dass selbst nach 10 aufeinanderfolgenden Zyklen keine Reduktion der katalytischen Aktivitat oder ein “Ausbluten” von Gold beobachtet werden konnte. Die Flexibilitat der vorgestellten Methode erlaubt eine einfache Ubertragung auf andere Tragerfasern und unterschiedliche katalytisch aktive NP, wodurch sich ein breites Anwendungsspektrum in der heterogenen Katalyse eroffnet.

One-dimensional patchy nanostructures are interesting materials due to their excellent interfacial activity and their potential use as carrier for functional nanoparticles. Up to now only wormlike crystalline-core micelles (wCCMs) with a nonfunctional patchy PS/PMMA corona were accessible using crystallization-driven self-assembly (CDSA) of polystyrene-block-polyethylene-block-poly(methyl methacrylate) (SEM) triblock terpolymers. Here, we present a facile approach toward functional, patchy wCCMs, bearing tertiary amino groups in one of the surface patches. The corona forming PMMA block of a SEM triblock terpolymer was functionalized by amidation with different N,N-dialkylethylenediamines in a polymer analogous fashion. The CDSA of the functionalized triblock terpolymers in THF was found to strongly depend on the polarity/solubility of the amidated PMMA block. The lower the polarity of the amidated PMMA block (increased solubility), the higher is the accessible degree of functionalization upon which define...

The carbon content of mesostructured organic-inorganic hybrid material of a cylindrical block copolymer template of poly(2-vinylpyridine)-block-poly(allyl methacrylate) (P2VP-b-PAMA) and ammonium paramolybdate (APM) could be reduced by thermal depolymerization. By calcination in vacuo at 320 °C the PAMA core can be completely removed while the remaining P2VP brush preserves the mesostructure. The P2VP-APM composite can then be carburized in-situ to MoOxCy in a second pyrolysis step without any additional carbon source but P2VP. The molybdenum oxycarbide nanotubes obtained, form hierarchically porous non-woven structures, which were tested as catalyst in the decomposition of NH3. They proved to be catalytically active at temperatures above 450 °C. The activation energy was estimated from an Arrhenius Plot to be 127 kJ·mol–1.

This work highlights the usage of short electrospun fibers for the first time for the preparation of homogeneous polymer nanofiber/polymer composites and the improvement in mechanical properties by an order to magnitude compared to as-electrospun long and continuous nanofibers. Dispersions of short electrospun nanofibers can be processed by liquid processing techniques resulting in nanofiber nonwovens similar to electrospun nonwovens but is independent from the demands of the electrospinning process is one of the emphasis of this work. The re-formation of electrospun fiber nonwovens by dispersion casting of short electrospun polyimide (PI) nanofibers and the preparation of homogeneous polymer/polymer nanofiber composite films were selected as representative examples for showing the versatility of short electrospun fibers. The self-reinforced PI/PI-short nanofiber composite films were obtained from mixtures of short electrospun PI nanofibers and polyamic acid after imidization. Significant improvement of 53% and 87% in mechanical properties like tensile strength and modulus, respectively in comparison to the neat PI film was observed by using just 2 wt% of short fibers. Parallel experiments were also carried out with long and continuous electrospun PI fibers and amazingly a huge difference was observed. The amount of continuously long fibers required for achieving almost the same strength was much higher i.e. 38 wt% in comparison to the 2 wt% required of short fibers.

Heterogeneous catalysis with supported nanoparticles (NPs) is a highly active field of research. However, the efficient stabilization of NPs without deteriorating their catalytic activity is challenging. By combining top-down (coaxial electrospinning) and bottom-up (crystallization-driven self-assembly) approaches, we prepared patchy nonwovens with functional, nanometer-sized patches on the surface. These patches can selectively bind and efficiently stabilize gold nanoparticles (AuNPs). The use of these AuNP-loaded patchy nonwovens in the alcoholysis of dimethylphenylsilane led to full conversion under comparably mild conditions and in short reaction times. The absence of gold leaching or a slowing down of the reaction even after ten subsequent cycles manifests the excellent reusability of this catalyst system. The flexibility of the presented approach allows for easy transfer to other nonwoven supports and catalytically active NPs, which promises broad applicability.