Helical polyurethane-imide with optical activity based on binaphthyl units: preparation, characterization, and study of interchain hydrogen bonds

Abstract

Helical polyurethane-imide with optical activity based on R-1,1′-binaphthyl-2′,2-diol (R-BINOL) and racemic polyurethane-imide (racemic-PUI) based on racemic 1,1′-binaphthyl-2′,2-diol (racemic-BINOL) were synthesized by hydrogen transfer addition polymerization procedure and characterized by 1H NMR spectra, Fourier Transform Infrared Spectroscopy (FT-IR), thermal Fourier transform infrared spectroscopy (thermal FT-IR), X-ray diffraction (XRD), circular dichroism (CD) spectroscopy and thermogravimetric analysis (TGA). R-PUI exhibits the single-handed helical conformation and optical activity via CD spectra analysis. The optical rotation of R-PUI is +55.0°, which is larger than that of R-BINOL. The thermal stability of R-PUI is higher than that of racemic-PUI by TG analysis. According to the FT-IR and thermal FT-IR analysis, R-PUI with single-handed conformation possesses prominently interchain hydrogen bonds interactions, which plays an important role in thermal stability and optical activity.