Sustainable and biobased self-blown polycarbonate foams: from synthesis to application†

Escalating environmental concerns driven by the continuous demand for fossil-based materials have sparked growing interest in designing biobased polymeric materials for high-added-value applications. A novel series of self-blowing polycarbonate foams derived from various biobased polyols (e.g. cashew nutshell liquid, vegetable oil, and lignocellulose) is reported by leveraging thiol-triggered carbon dioxide release in a formulation composed of a thiol and 5- and 6-membered cyclic carbonates. The polyol architecture enabled a tunable open-cell morphology and properties, achieving up to 41 wt% biobased content, marking the first incorporation of biobased monomers in this type of foam. In this context, cashew nutshell-based foam featured good cyclic endurance at 70% compression and a high-water uptake capacity of 8 g g⁻¹. As a forward-looking solution to address environmental challenges, this foam effectively supports the germination of different types of vegetable seeds (e.g. bok choy (Brassica rapa chinensis), lettuce (Lactuca sativa), and radish (Raphanus sativus)) in soilless environments, and its hydrolytic stability ensures reusability for subsequent seedling growth. This study lays the foundation for designing future environmentally friendly and renewable polymeric foams that are potentially recyclable with sustainable applications, e.g., in hydroponics.