Anisotropic nanofiber scaffold
Figure 2 shows polarization dependent transmission and phase spectra of the nanofiber sample for 0° and 90° azimuthal rotation. The observed band at about 1240 cm–1 is assigned to the asymmetric C–O–C stretching vibration (according to Ref.40) of the PCL chain. The onset of a second vibrational band at about 1293 cm–1 is observed at the edge of the investigated spectral range. Qualitative and quantitative agreement in band position, amplitude and shape is found between the corresponding sets of polarized transmission IR-DCP and FTIR polarimetric spectra. A strong anisotropy is identified in the range of the C–O–C vibrational band. This anisotropy originates from the direction-dependent vibrational absorption due to the predominant alignment of polymer chains within single fibers, but also due to the overall close-to-parallel orientation of the individual fibers41,42. Qualitative agreement is observed between the relative phase difference spectra obtained from IR-DCP and FTIR polarimetry (Fig. 2(b)).