This study highlights the stereochemical effects isohexide isomer content has on the material properties of biomass derived polyurethanes. These materials were synthesized from 2,5-bishydroxymethylfuran (BHMF) and either isosorbide bis(3-isocyanatopropanoate) (ISBIP) or isomannide bis(3-isocyanatopropanoate) (IMBIP) at varying feed ratios. 1H-NMR and optical rotation data confirm the desired isohexide feed ratios incorporated into the resulting polymers. All polyurethanes were found to be thermally stable with decomposition temperatures (Td, onset) ~ 240 °C and glass transition temperatures (Tg) ~ 42 °C. Uniaxial tensile testing found that all materials were strong (E &gt; 1 GPa) but brittle (ε &lt; 2 %), typical of glassy polymers. Purely isosorbide based polyurethanes were found to be lightly entangled, where isomannide polyurethanes were unentangled at similar molar masses. The presence of entanglements results in an increased density, reduced fractional free volume, and a tougher material. When the two isomers were mixed into the polymer, the resulting material showed a drastic increase in brittleness.

Synthesis of renewable polyurethanes derived from isohexides and furans: Stereochemical effects on mechanical and viscoelastic properties

255th National Meeting (2018)

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