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)).