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

Abstract

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.

Patchy Micelles with a Crystalline Core: Self-Assembly Concepts, Properties, and Applications

“…The resulting patchy nonwovens were loaded with gold NPs through a simple dip-coating process ( Figure 11 c), which was driven by a ligand exchange reaction. The hybrid nonwovens were successfully applied as catalysts for the alcoholysis of dimethylphenylsilane ( Figure 11 d) at room temperature, showing a comparable or even higher catalytic activity than other supports reported before [ 188 , 189 , 190 , 191 , 192 , 193 ]. Moreover, the employed patchy hybrid nonwovens were easily recoverable from the reaction medium and reusable in at least 10 consecutive catalysis cycles.…”

Block Copolymers with Crystallizable Blocks: Synthesis, Self-Assembly and Applications

“…The resulting patchy nonwovens were loaded with gold NPs through a simple dip-coating process (Figure 11c), which was driven by a ligand exchange reaction. The hybrid nonwovens were successfully applied as catalysts for the alcoholysis of dimethylphenylsilane (Figure 11d) at room temperature, showing a comparable or even higher catalytic activity than other supports reported before [188][189][190][191][192][193]. Moreover, the employed patchy hybrid nonwovens were easily recoverable from the reaction medium and reusable in at least 10 consecutive catalysis cycles.…”

Stable Mesoscale Nonwovens of Electrospun Polyacrylonitrile and Interpenetrating Supramolecular 1,3,5-Benzenetrisamide Fibers as Efficient Carriers for Gold Nanoparticles

“…To ensure high catalytic reaction rates, AuNPs should have, in general, a very high surface area. − However, because of insufficient stabilization, AuNPs often tend to agglomerate to reduce their surface energy . To circumvent agglomeration, AuNPs are usually stabilized by colloidal ligands or immobilized on the surface of support materials such as polymers or metal–organic frameworks. − Different research groups have used electrospun polymer nonwovens as a support to immobilize AuNPs and demonstrated their applicability for different catalytic reactions. − For instance, Liu et al showed the preparation of gold/polyacrylonitrile (Au/PAN) electrospun nonwovens for the 4-nitrophenol reduction combining electrospinning, amination, and the electroless plating technique. Efficient immobilization of AuNPs on the electrospun PAN fibers was achieved by introducing amine and imide groups onto the fibers’ surface .…”

“…Another approach was reported by our group, who developed tea-bag-type carriers based on electrospun polymer fibers and nanotubes for the efficient immobilization of AuNPs. We demonstrated that these systems can be beneficial being used and reused for catalytic alcoholysis. ,, In this kind of system, leaching of the catalyst is still an unresolved issue.…”

“…We demonstrated that these systems can be beneficial being used and reused for catalytic alcoholysis. 7,16,19 In this kind of system, leaching of the catalyst is still an unresolved issue.…”