High-performance thermotropic starch-based liquid crystalline polymer

A thermotropic starch liquid crystalline polymer (St-10CN) was successfully synthesized by high-degree substitution (esterification) of the hydroxyl groups resided on the starch with mesogenic 11-(4′-cyano-biphenyl-4-yloxy)-undecanoic chloride in the presence of pyridine. The degree of substitution of St-10CN was calculated to be 2.68 based on the result of elemental analysis. The chemical structure of the polymer was confirmed using Fourier transfer infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy. The thermal transitions of St-10CN were determined using differential scanning calorimetry and its mesophase structures were characterized using polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). This unique starch-based side-chain liquid crystalline polymer is glassy and smectic with excellent thermal stability, and has tensile strength of 37.9 ± 7.0 MPa and Youngʹs modulus of 1.42 ± 0.14 GPa.