Polymer-metal nanocomposites with bi- or tri-metallic compositions exhibiting catalytic properties

Abstract

Heterogenous catalysis using hybrid materials such as polymer-metal nanocomposites (PMNCs) are rapidly gaining attention in recent years for their enhanced catalytic performance due to their significantly different physicochemical properties compared to their larger counterparts. Traditional techniques of preparing PMNCs uses capping/stabilising agents which wraps around metal nanoparticles (MNPs), forming a barrier that limit active site availability and reduce catalytic efficiency. This paper presents an approach to prepare gold (Au), palladium (Pd) and silver (Ag)-based PMNCs in situ via ultrasonic treatment with unobstructed MNPs attached to amine functionalities located on the surface of polymeric chains synthesised from reversible addition−fragmentation chain-transfer (RAFT) polymerisation-induced self-assembly (RAFT-PISA). High resolution transmission electron microscopy (HR-TEM) imaging and energy-dispersive x-ray (EDX) mapping confirmed the successful preparation of these PMNCs. The catalytic performances of these PMNCs are evaluated against well-known organic reactions such as 1-phenylethanol aerobic oxidation and the Suzuki-Miyaura cross-coupling reaction between 4-iodophenol and phenylboronic acid, where the performance of the bimetallic Au-Pd PMNC and the bimetallic Ag-Au PMNC reached as high as 94% and 98.5% for each respective reaction at 0.02 mol% concentration. Additionally, the catalytic performance of the trimetallic Ag-Au-Pd PMNC was discovered to be 39.8% and 96.0% respectively for both reaction at the same concentration. This work aims to expand on the knowledge of PMNCs and promote their utility as advanced heterogenous catalysts in organic reactions.