Encapsulation of Homogeneous Catalysts in Porous Polymer Nanocapsules Produces Fast-Acting Selective Nanoreactors

Abstract

Nanoreactors were created by entrapping homogeneous catalysts in hollow nanocapsules with 200 nm diameter and semipermeable nanometer-thin shells. The capsules were produced by the polymerization of hydrophobic monomers in the hydrophobic interior of the bilayers of self-assembled surfactant vesicles. Controlled nanopores in the shells of nanocapsules ensured long-term retention of the catalysts coupled with the rapid flow of substrates and products in and out of nanocapsules. The study evaluated the effect of encapsulation on the catalytic activity and stability of five different catalysts. Comparison of kinetics of five diverse reactions performed in five different solvents revealed the same reaction rates for free and encapsulated catalysts. Identical reaction kinetics confirmed that placement of catalysts in the homogeneous interior of polymer nanocapsules did not compromise catalytic efficiency. Encapsulated organometallic catalysts showed no loss of metal ions from nanocapsules suggesting stabilization of the complexes was provided by nanocapsules. Controlled permeability of the shells of nanocapsules enabled size-selective catalytic reactions.

Recycable complex catalysts immobilized on mercaptan-functionalized glass-polymer supports

“…These catalysts were evaluated for their performance in the Heck and hydrogenation reaction. The direction of the research is consistent with the research conducted in the world [12][13][14][15].…”

Functionalization of Hollow Nanomaterials for Catalytic Applications: Nanoreactor Construction

“…Hence, encapsulation in the voids of hollow structures is a valid strategy to stabilize particle catalysts as well as molecular catalysts without the inhibition of reactive sites. Dergunov et al confined five types of homogeneous catalysts inside the porous polymer nanocapsules with nanosized semipermeable thin shells to construct nanoreactors for the systematic investigation of catalytic activity and stability toward five different reactions, i.e., acylation of alcohols, Suzuki coupling reactions, Sonogashira coupling reactions, heterocyclization, and epoxidation . Evaluation results verified that the encapsulated catalysts exhibited the same activity as the free‐standing catalysts, and no loss of metal ions and activity was detected during the tests.…”

“…In addition, the uniform pore size of the shell contributes to the size‐selected catalysis, particularly for large organic molecule participated reactions . Molecular sieving effect by utilizing steric effect is similar to the specific transport of protein‐conducting channels on the cytomembrane.…”

Bilayer‐Templated Two‐Dimensional RAFT Polymerization for Directed Assembly of Polymer Nanostructures

“…In the past, we and others used the free‐radical polymerization of hydrophobic monomers in the hydrophobic interior of different assemblies of amphiphilic molecules to produce nanocapsules, nanodisks, and nanorods . Nanocapsules, having an average diameter programmed between 40 to 400 nm with narrow size distribution and the ability to entrap and retain molecules and nanoparticles, showed utility in diverse applications, such as nanoreactors, nanosensors, and containers for the delivery of drugs and imaging agents . The formation of hollow vesicle‐templated nanocapsules and the ability to imprint programmed nanopores was demonstrated by a combination of electron microscopy, dye retention, and scattering techniques .…”