Step-growth polymerization of 10,11-epoxyundecanoic acid. Synthesis and properties of a new hydroxy-functionalized thermoplastic polyester

Oxidation of undecylenic acid, a derivative of castor oil, affords 10,11-epoxyundecanoic acid (5). In the presence of a quaternary ammonium or phosphonium bromide as an initiator, monomer 5 undergoes an AB polymerization via nucleophilic ring-opening of the epoxide group with the carboxylic acid moiety to yield high-polymeric hydroxy-functionalized aliphatic polyester (6). Polymer 6 is a crystalline thermoplastic (T_m = 97 °C) that exhibits yield stress, break stress and elongation (9.7 MPa, 24.1 MPa and 450%) very similar to those of linear low density polyethylene. However, in contrast to the behavior of the polyolefin and owing to the pendent hydroxyl moieties of 6, films of the polyester adhere strongly to metallic substrates and have moderately good barrier to oxygen. In addition to physical properties of 6, the effect of the initiator utilized in the polymerization of 5 on the molecular weight and polydispersity of product 6 is discussed.