Ordered structures in polycarbonate studied by infrared and Raman spectroscopy, wide-angle X-ray scattering, and differential scanning calorimetry

Ordered structures in samples of Bisphenol A polycarbonate (BPAPC) prepared by varying thermal and solvent conditions were investigated by infrared and Raman spectroscopy, wide-angle X-ray scattering (WAXS), and differential scanning calorimetry(DSC). Based on the spectroscopic analysis and ab initio quantum mechanical calculations of diphenyl carbonate as a model compound, an assignment of the bands conformationally sensitive to the trans-trans and cis-trans structures is proposed. Temperature dependences of the vibrational spectra of BPAPC show that cis-trans structure is the energetically preferred conformation in the amorphous state and in solution and its population can be increased with decreasing temperature in amorphous BPAPC even below the glass transition temperature. Differences in the degrees of ordering in semicrystalline BPAPC assessed from the vibrational spectra, WAXS, and DSC indicate partial order in the interfacial region between the crystalline and amorphous phases. In some solvents (toluene, benzene), aggregation of BPAPC occurs, leading to the ordered structure analogous to crystalline BPAPC. The order is preserved in semicrystalline BPAPC obtained by the room-temperature evaporation of the solvent.