Enzyme- and Metal-Catalyzed Synthesis of a New Biobased Polyester

Linear aliphatic polyesters were prepared from Pripol 1012, a diacidic C18 fatty acid dimer, and 1,3-propanediol employing a lipase or a titanium tetrabutanoate. Metal-based catalysis (route M) was carried out with a precondensation at 180 degrees C and 600 mbar followed by a final condensation at 220 degrees C and 0.3-0.6 mbar. Enzyme catalysis was carried out with an immobilized Candida antarctica lipase B after either a precondensation step at 180 degrees C and 600 mbar (route El) or 80 degrees C and 100 mbar (route E2) and a final condensation at 80 degrees C and 0.3-0.6 mbar. Polyesters were obtained along routes M, El, and E2 with weight-average molecular weights, M-W, at final conversion of 84.6, 26.7, and 15.6 kg mol(-1), respectively. The final molecular weight via route E2 was most probably constrained by depletion of 1,3-propanediol during precondensation. Rheological measurements of the polyesters in melt revealed a Newtonian-like behavior at 80 degrees C. The dynamic viscosities fulfill the Cox-Merz rule. The power law for the viscosity as a function of M-W, possesses an exponent of 3.7 +/- 0.2. A polyesterdiol of M-n approximate to 6 kDa prepared along route M was used in the synthesis of a polyurethane elastomer with a Young modulus of 2.5 MPa, an elongation at break of 554%, an ultimate tensile strength of 3.5 MPa, and a Shore A hardness of 38.