CO2-based, crosslinked poly(hydroxyl urethane)s (PHUs) are accessed via a set of efficient reactions based on the addition chemistry of thiol-ene and amines-cyclic carbonates. This strategy to utilize 5-membered cyclic carbonates produced from CO2 is robust, facile, modular, and atomically efficient in nature. The thiol-ene reaction was utilized to access bis(cyclic carbonate), tris(cyclic carbonate), and tetrakis(cyclic carbonate) in quantitative yield from 4-vinyl-1,3-dioxolan-2-one and thiols. Multi-functional cyclic carbonates were simply mixed with diethylenetriamine and/or 1,6-diaminohexane to generate crosslinked PHUs from 25 to 80 degrees C. These materials are easy to scale-up and are potential candidates in many applications such as coatings, binders, and resins. The resulting polymers have glass transition temperatures between -1 and 16 degrees C and thermal decomposition temperatures from 190 to 230 degrees C. (C) 2011 Wiley Periodicals, Inc.(dagger) J Polym Sci Part A: Polym Chem 49: 2024-2032, 2011