Polyurethane compounds are useful in many commercial applications, including high-performance adhesives, surface coatings, sealants, binders, hydrogels, and resins. A polyurethane compound is any polymer composed of a chain of organic units joined by carbamate (—NCOO—) links. Polyurethanes are conventionally formed by the reaction of a diisocyanate and polyfunctional compounds in the presence of a catalyst. A major disadvantage of this synthesis method is the use of monomers containing toxic isocyanate groups. Recent emphasis has been placed on producing polyurethanes without the use of isocyanate through the reaction of a diamine and a molecule having one or more cyclic carbonate functional groups. Compounds resulting from this synthetic route are referred to as poly (hydroxyl urethanes) (PHUs) due to the presence of primary and/or secondary hydroxyl functional groups.

The current technology provides a single-step method for the synthesis of crossed-linked PHUs from CO₂-based intermediates. Crossed-linked compositions are obtained through the use of cyclic carbonate chemistry involving the reaction of a CO₂-derived cyclic carbonate, a thiol, and a compound having two or more amine functional groups. The synthetic process is efficient, simple, flexible, and scalable allowing for the production of less toxic, non-isocyanate containing PHU composites having adhesive properties.