Thermoplastic polyurethanes (TPU) are a broad class of macromolecules composed of chemically dissimilar units commonly denoted as hard and soft segments. Due to the extensive diversification of possible chemical constituents, a rather wide variety of mechanical properties are accessible from these materials. In a recent report by our laboratory and collaborators, a biotechnological route to w-hydroxytetradecanoic acid (w-HOC14) was disclosed. An engineered strain of the diploid yeast Candida tropicalis was developed that produces commercially viable yields of w-OHC14. In this work, w-HOC14 was converted by a condensation polymerization catalyzed by titanium tetraisopropoxide (Ti[OiPr]4) to a series of polyester polyols with variable quantities of w-HOC14, 1,4-butanediol (BD) and adipic acid (AA) units.  High hydroxyl end group fidelity was achieved allowing the successful synthesis of a series of thermoplastic polyurethanes (TPU) with Mw values of about 100K. Two-series of TPU's were prepared: i) with copolyester polyols having with varied contents of w-HOC14, BD and AA units and ii) varied ratios of BD-capped w-HOC14 and AA-BD polyols. Studies will be reported on the thermo-mechanical properties of the resulting polyols that present in different ways variable contents of w-HOC14 units.  With increasing w-HOC14 content in the polyols of corresponding TPU's, the tensile strength increased from 30 MPa to 470 MPa while the %-elongation decreased from 900 to 300%. Thus, by increasing the w-HOC14 content in TPU's their mechanical properties shifted from elastomeric to semi-crystalline thermoplastics. In summary, benefits achieved by incorporating an w-hydroxylated fatty acid include: i) increasing the bio-content of TPUs, ii) at moderate w-HOC14 contents elastomeric TPU's were obtained that have increased tensile strength and stress at break, iii) based on structure we anticipate that the introduction of w-hydroxylated fatty acid units in TPU's will also increase the materials resistance to hydrolysis and microbial mediated erosion.

Improving thermoplastic polyurethane performance by building polyols from bio-derived w-hydroxyfatty acid units

248th National Meeting (2014)

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