Significant energy is expended on the extraction and purification of raw materials that comprise the advanced infrastructure on which modern society is built. Despite these investments in the extraction of petrochemicals and minerals, their commercial products are generally simply disposed at the end of their service life. This linear materials economy of take-make-dispose fails to exploit the inherent energy value of the materials in the disposed products, but also inevitably leads to significant carbon requirements for the heavy vehicles associated with mining and oil extraction as well as energy for materials purification and chemical transformations. In order to close the carbon cycle, the minimization of fossil fuel driven heavy vehicles, decreasing the overall energy duty for materials manufacture, and maintaining carbon from plastics in the value chain are critical components. Here we describe an intrinsically low energy processing route that provides potential for upcycling of waste materials through combining typically incompatible inorganic-organic materials that provides intriguing combinations of strength and toughness. These materials are enabled by cold sintering, a nascent technology for low temperature sintering of ceramics through dynamic dissolution-precipitation, which relies on the small but finite solubility of the inorganic material in a volatile solvent. With processing temperatures &lt; 200°C, cold sintering opens new pathways for inorganic-organic hybrid composites where the properties are defined by the structure that develops through the processing.  Gypsum, a generally downcycled building material, and polypropylene, a common but challenging to recycle plastic, are shown to produce tough materials with co-continuous organic and inorganic phases from cold sintering. The synergistic increases in strength and toughness occurs when the average domain sizes are less than approximately 200 microns. These composites can be simply recycled through grinding and re-sintering with no degradation in the properties. The reprocessing involved modest pressures, heating to 150 °C and the addition of a minimal amount of water. With the increasing use of standard polymer composites, we postulate that cold sintering represents a low energy route to effectively keep the carbon in these composites in play with demonstrated potential for circularity with enhanced properties to present opportunities for upcycling.

Enabling circularity in disparate difficult to recycle materials through cold sintering

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.