Self-Assembled Catalytic Nanoreactors from Molecular Brushes by Utilizing Postpolymerization Modification for Catalyst Attachment

Abstract

Polymer-based catalytic nanoreactors, with the characteristics of easy preparation, good dispersion, and facile modulation of molecular structures, have been widely applied for various organic transformations. Usually, polymeric nanoreactors are fabricated via the self-assembly of amphiphilic copolymers in water, while the disassembly and instability of the relevant nanoreactors often compromise their potential applicability. Molecular brushes (MBs), as a kind of polymer with high-density grafted side chains on the linear polymer main chain, can be rapidly self-assembled into highly ordered nanostructures even at low concentrations. This study reports the fabrication of catalytic nanoreactors from molecular brushes of poly­[norbornene–poly­(bromoethyl methacrylate-co-methyl methacrylate)]-co-poly­[norbornene polyethylene glycol monomethyl ether] (P­[NB-(BEMA-co-MMA)]-co-P­[NB-PEG]). The amphiphilic molecular brush was synthesized by combining reversible addition–fragmentation chain transfer (RAFT) polymerization and ring-opening metathesis polymerization (ROMP) techniques. Homogeneous catalysts, such as triethylenediamine and 4-(dimethylamino)­pyridine analogues, were introduced by nucleophilic substitution with alkyl bromide on the side chain of molecular brushes. Furthermore, micellar catalytic nanoreactors were fabricated via self-assembly in deionized water. The resulted nanoreactors display high catalytic activities toward the Knoevenagel condensation reaction and acylation reaction of alcohol in water, respectively. This contribution describes a general method for constructing highly efficient molecular brush-based catalytic nanoreactors utilizing postpolymerization modification (PPM) for aqueous catalysis.

Spiropyran-based polymeric micelles in aqueous solution: light-regulated reversible size alterations and catalytic characteristics

“…As we all know, one of the most important organic transformations in organic synthesis is the formation of carbon-carbon bonds catalyzed by using weak bases like amines and their related ammonium salts. 49,50 Next, we used M2 as a photoresponsive catalytic nanoreactor to catalyze the classical Knoevenagel condensation reaction (Fig. 5).…”

Recent advances in the self-assembly of sparsely grafted amphiphilic copolymers in aqueous solution

“…10). 149 Since the polarity and hydrophobicity of the hydrophobic core of the polymer aggregate can be controlled by changing the side-chain-modification rate of the graft copolymer, the properties required for the reaction field can be easily optimized. Accordingly, it is envisioned that graft copolymer-based nanoreactors will attract increasing research attention.…”

PET‐RAFT polymerization under flow chemistry and surface‐initiated reactions

“…The introduction of amphiphilic polymers in a suitable solvent can create self-assembled nanostructures with significant potential use in nanoreactors, 55 catalysts, 56 drug release 57 lengthy preparation time and low solid content, PISA usually only requires minutes to hours to complete the preparation, with the advantage of achieving high solid contents by dispersion or emulsion polymerization. 58 Although performing PISA in a batch may result in marked variations, 59 using a flow reactor capable of employing continuous polymerization may help reduce such variations and further increase the production rate.…”

“…The introduction of amphiphilic polymers in a suitable solvent can create self‐assembled nanostructures with significant potential use in nanoreactors, 55 catalysts, 56 drug release 57 and the like. Polymerization‐induced self‐assembly (PISA) has been developed to overcome the limitations of large‐scale preparation of nanostructures.…”