carbodiimide chemistry from isocyanates: advancing hydrolysis resistance in polyester and polyurethane materials

Polyethylene terephthalate (pet) and polyurethane (pu) are widely used in industrial and consumer applications due to their favorable mechanical, thermal, and chemical properties. nevertheless, their ester and urethane linkages are intrinsically susceptible to hydrolytic degradation, particularly in humid or aqueous environments, leading to reduced service life and compromised performance. this review highlights the carbodiimides synthesis from isocyanates and their functional role as hydrolysis stabilizers in pet and pu systems. recent advances in carbodiimide chemistry, including novel synthetic methodologies, structure–property relationships, and integration into polymer matrices, are critically examined. the review also explores the synergistic interactions of carbodiimides with antioxidants and uv stabilizers, as well as their incorporation via melt blending, reactive extrusion, and other processing techniques. emerging directions such as bio-based and reactive carbodiimides, non-migratory formulations, and environmental and toxicological considerations are discussed. the review concludes with a forward-looking perspective on the role of carbodiimides in enhancing polymer durability within sustainable material frameworks.