Polyether based thermoplastic polyurethanes (TPUs) have been widely used in biomedical applications due to a broad range of physical properties. However, these polymers are highly susceptible to oxidative degradation leading to a deterioration of mechanical properties. Recently introduced polyisobutylene (PIB) based TPUs exhibit excellent oxidative and hydrolytic stability, however, the precursor PIB diol is not available commercially. Generally, TPUs based on nonpolar soft segments possess lower tensile strength and toughness due to premature phase separation, especially in bulk synthesis, leading to compositional heterogeneity. We have investigated the preparation of poly(ethylene-butylene) (PEB) based TPUs by a two-step solution-based synthesis. The tensile strength of the prepared TPUs were still inferior compared to polyether based TPUs, however, addition of a small amount of polyether diol dramatically increased the tensile strength and ultimate elongation. All polyurethanes were completely amorphous with a Tg = -42 °C, a bit higher than the Tg of PEB (~-50°C), indicating some phase mixing. Accelerated metal ion oxidative degradation studies were carried out in 20% H2O2 solution containing 0.1 M CoCl2 at 50 °C for 12 weeks. After 12 weeks the TPU retained 90% of its weight, 79% of tensile strength and 85% of ultimate elongation, indicating superior stability, similar to PIB based TPUs.

Synthesis, characterization and biostability of poly(ethylene-co-butylene) polyurethanes

256th National Meeting (2018)

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