Baroplastics – The future of low temperature plastic processing

Abstract

While global annual plastic production has surpassed 400 million tons, the rate of plastic recycling remains below 10 %. Recycling rates for conventional thermoplastics remain low, largely due to the harsh conditions required for high-temperature melt-molding. These conditions promote thermo-oxidative reactions and chain scission, causing significant deterioration of polymer chains and reducing the recyclability of these materials. Additionally, the sustainability of this process is compromised by its high energy demands and harmful environmental impacts. Baroplastics provide an alternative recycling pathway that involves the use of low-temperature processing under pressure; a novel class of sustainable polymers that leverages their unique pressure-responsive properties to enable recycling at markedly reduced energy consumption and CO₂ emissions. Baroplastics rely on order-to-disorder transitions (ODTs), typically of block copolymers (BCPs), that allow for a rheological transition from an ordered solid to a disordered liquid-like state that can flow and be molded. Once pressure is removed, the liquid-like state returns to its original solid form with no observed degradation of the polymeric chains. In this review, we introduce the concept of baroplastics and explore the mechanisms that underpin their distinctive ability to flow under pressure for sustainable recycling. We discuss the technological and environmental advantages of baromechanical recycling, the potential for future implementation within industry, and the use of baroplastics in nanocomposites and biological systems. Moreover, we have thoroughly reviewed the scope, modelling, and synthesis of baroplastic materials to produce a guide to this growing field.