1,3-Dioxan-2-one, also known as trimethylene carbonate, is primarily used as a monomer in ring-opening polymerization to synthesize poly(trimethylene carbonate) (PTMC), a flexible and biodegradable aliphatic polycarbonate. It is commonly incorporated into copolymers with monomers like lactide or glycolide to produce materials with adjustable mechanical properties, degradation rates, and biocompatibility, ideal for biomedical applications such as resorbable sutures, controlled drug delivery systems, and tissue engineering scaffolds. The polymerization process enables precise control over molecular weight and results in low-toxicity products. It also plays a role in green chemistry as a building block for sustainable, renewable, and compostable plastics derived from bio-based 1,3-propanediol.