Synthesis, helicity, thermal stability, and low infrared emissivity of optically active polyacetylenes carrying tyrosine pendants

Optically active polyacetylenes (LPA and DPA) and racemic polyacetylenes (RPA) were prepared by the polymerization of N-propioloyl-tyrosine methyl esters that derived from chiral and racemic tyrosine. All the polymers were characterized by Fourier transform infrared spectroscopy, 1H NMR, 13C NMR, gel permeation chromatography, thermogravimetric analysis, UV–vis spectroscopy, and circular dichroism spectroscopy; furthermore, the infrared emissivity values were also investigated. Both LPA and DPA possessed the helical conformations and a higher degree of intra- and interchain hydrogen bonds compared with RPA, which presented irregular polymer chain. The thermal stability of LPA and DPA was higher than that of RPA due to the helical conformations, which could be easy to form a high degree of intra- and interchain hydrogen bonds in the structure. Therefore, LPA and DPA exhibited lower infrared emissivity values (8–14 μm) than that of RPA, which resulted from the helical conformations and a higher degree of intra- and interchain hydrogen bonds.