Scalable synthesis of methacrylate-based vitrimer powders by suspension polymerization

Abstract

The synthesis of covalent adaptable network polymers is generally conducted in bulk, leading to a crosslinked polymer mass that is challenging to handle and process directly. Here, we present an alternative process that leads to a free flowing powder that can be easily transported and processed without further modification. To achieve this, the suspension copolymerization of butyl methacrylate is performed in the presence of a vinylogous urethane-based methacrylic crosslinker. Control of the primary chain length is achieved by using an alkoxyamine initiator, while the crosslink density is controlled by the concentration of crosslinker. The obtained crosslinked powder can be processed by compression molding at elevated temperatures and the vitrimeric character, which can be controlled by alterations to the polymer structure, is confirmed through a series of rheological measurements. Furthermore, in order to demonstrate the flexibility of the synthetic pathway proposed, polymers with different glass transition temperature were obtained by changing the methacrylic monomer to ethyl and 2-ethylhexyl methacrylate. It was found that materials present similar relaxation behaviour despite having different mechanical properties at room temperature.