Stereoselective Crystallization and Specific Interactions in Polylactides

摘要: The stereoselective annealing conditions for polylactides to crystallize as α homocrystals (Tm = 180 °C) and/or higher melting temperature 230 η stereocomplex crystals are reported in this paper. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies provide evidence of the isothermal which equimolar mixtures optically pure poly(l-lactide) poly(d-lactide) take exclusively form α, η, or coexist both crystal polymorphs. Fourier transformed infrared (FTIR) spectroscopy reveal a shift lower wavenumbers CO stretching band with regard that homocrystal. This is accompanied by similar displacements C−H spectral bands. These results interpreted terms H-bonding forces causing specific CH3···OC CαH···OC interactions between stereoisomers polylactide. Molecular models support suggested hydrogen-bonding arrang...