Polymer, Vol.92, 140-152, 2016
Imparting elastomeric properties to entirely lipid-derived thermoplastic poly(ester urethane)s: Molecular weight control
High molecular weight, thermoplastic poly(ester urethane) (TPEU) elastomers were synthesized from oleic-acid derived polyester diols (PED)s and 1,7 heptamethylene diisocyanate (HPMDI). Functional group stoichiometry and polymerization time were used to control molecular weight and optimize thermal and mechanical properties. A targeted range of PEDs with controlled molecular weights and consistent dispersity were obtained in high yields using an induced stoichiometric imbalance method. The PEDs were reacted with HPMDI with different NCO: OH ratios (1.1-2.1) and polymerization times (2-24 h) to obtain high molecular weight TPEUs. Solvent-resistant TPEUs, displaying polyethylene-like behavior were obtained and characterized by GPC, FTIR, DSC, XRD, TGA, DMA and tensile tests in order to reveal the structure-property relationships. Melting temperatures, tensile strength and maximum strain scaled with molecular weight approaching saturation values, demonstrating a plateau effect of molecular weight on physical properties. The entirely lipid-derived TPEUs exhibited thermal and mechanical properties comparable to commercial, petroleum-based analogues. (C) 2016 Elsevier Ltd. All rights reserved.