Polyesters from Large Lactones

Ann-Christine Albertsson, Indra K. Varma, and Rajiv K. Srivastava 

Handbook of Ring-Opening Rdynterization. Edited by P. Dubois, O. Coulembier, and J.-M. Raquez Copyright 2009 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31953-4 

In this chapter we will discuss the ROP and copolymerization of medium-ring sized (i.e. 7- to 11-membered) and large ring lactones (12- to 17-membered), using nonenzymahc (anionic, cationic and organometallic initiators) as well as enzymatic methods. The preparation of polyesters with pendant functionality or end-functionality will also be described, and the physical properties and potential applications of such polyesters briefly mentioned. 

---

The production of polyesters from lactones (cyclic esters) avoids the problems usually encountered in traditional polyester synthesis due to esterification equilibrium and water production. In fact, they yield in a single step, in the presence of ROP catalysts, high molecular weight polymers endowed with optimum mechanical properties. This is particularly true when large lactones are used as starting monomers. On the other hand, one of the main drawbacks connected with their use lies in their high cost. 

The Upase-catalyzed ROP of small-, medium- and large-ring lactones has often been reported. By definition. Upases hydrolyze triglycerides in an aqueous medium at one or more of the three ester bonds, and have been characterized by their drastically increased activity at the Hpid-water interface of a micellar or emulsified substrate. In a nonpolar medium, these enzymes are capable of initiating the ROP of cychc lactones, and this properly has been exploited for the synthesis of polyesters, especially from macrolides. 

---