Correlation between Secondary Structure and Interchain Hydrogen Bond in Helical Polyurethanes: Effect on the Infrared Emissivity

摘要

Optically active polyurethanes (PUs) with different specific rotations weresynthesized by the hydrogen transfer addition polymerization procedure of isocyanate-phenolswith different enantiomeric excess. The relationship between secondary structure and hydrogenbond was examined by FT-IR, UV–Vis spectroscopy, circular dichroism (CD) spectroscopy,X-ray diffraction (XRD) and thermaogravimetric analysis (TGA), and the infrared emissivityvalues (8-14 μm) of the PUs were investigated in addition. An approximately linear dependence ofthe optical activity on the amount of enantiomeric excess was observed. The enhancement ofenantiomeric excess increased the amount of orderly secondary structure of polymers with morecompact arrangement of macromolecular backbones. This facilitated the formation of a largenumber of inter-chain hydrogen bonds, and the infrared emissivity values of the correspondingPUs were decreased along with these. The results showed that the orderliness and hydrogenbondings in the macromolecular had great effect on the infrared emissivity.