Provided are methods forming polymers. The methods include, for example, tandem carbonylation and polymerization reactions, where epoxides are catalytically carbonylated to form lactones and the lactones catalytically polymerized to form polymers without the need to isolate or purify the lactone intermediate. Also provided are methods for catalytically polymerizing beta-propiolactone. Homopolymers and copolymers can be formed using the methods disclosed herein.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
 This invention was made with government support under contract nos. CHE-0809778 and DE-FG02-05ER15687 awarded by the National Science Foundation and the Department of Energy, respectively. The government has certain rights in the invention.