The Candida antarctica lipase B (Novozyme-435)-catalyzed ring-opening polymerization of omega -pentadecalactone in toluene was performed. Poly(w-pentadecalactone) [poly(PDL)] was obtained in a 93% isolated yield in 4 h with a number-average molecular weight of 64.5 x 10(3) g/mol. and a polydispersity index of 2.0. The solid-state properties of poly(PDL) were investigated by thermogravimetric analysis (TGA) coupled with mass spectrometry, differential scanning calorimetry (DSC), stress-strain measurements, wide-angle X-ray diffraction, and dynamic mechanical and dielectric spectroscopies. Poly(PDL) is a crystalline polymer that melts around 100 degreesC. The polyester shows good thermal stability, with a main TGA weight loss centered at 425 degreesC. Because of the high degree of poly(PDL) crystallinity, the glass transition (-27 degreesC) is revealed by relaxation techniques such as dynamic mechanical and dielectric spectroscopies, rather than by DSC. In addition to the glass transition, the viscoelastic spectrum of poly(PDL) also shows two low-temperature secondary relaxations centered at -130 (gamma) and -90 degreesC (beta). They are attributed to local motions of the long methylene sequence (gamma) and complex units involving water associated with the ester groups (beta). The mechanical properties of poly(PDL) are typical of a hard, tough material, with an elastic modulus and yield parameters comparable to those of low-density polyethylene.