Limonene as a Renewable Platform Molecule: Chemical Modifications and Polymerization Strategies toward Advanced...

Significant reliance on petroleum-based plastics remains due to their attractive properties and wide-ranging applications. Driven by environmental concerns, recent research has increasingly focused on utilizing naturally occurring plant-derived molecules and environmentally friendly processes for the synthesis of novel polymeric materials with adequate properties to replace petroleum-based materials. Within this context, limonene has gained unusual prominence as an abundant citrus byproduct. This terpene can be functionalized through a variety of classical organic reactions, e.g., epoxidation, (meth)-acrylation, lactam formation, and thiol-ene click chemistry, opening distinct pathways toward structurally diverse polymers. These routes span traditional radical and ionic processes, as well as coordination systems and ring-opening polymerizations. Together, they have enabled materials that range from poly-(limonene carbonates) and semiaromatic polyesters to polyethers, biobased polyamides, thermosets, and photo-cross-linkable resins suitable for 3D and 4D printing. Many of these polymers have demonstrated promising optical, mechanical, or thermal performance, although important challenges persist, particularly regarding dispersity control and the integration of recycling strategies into circular economy cycles. By bringing these developments into a single narrative, this review highlights how limonene is gradually shifting from a fragrance molecule to a versatile precursor for advanced, renewable polymeric materials.