Polarized FT-IR Study of Uniaxially Aligned Electrospun Poly(DL-Lactic Acid) Fiber Films

Abstract

Randomly deposited or uniaxially aligned electrospun poly(DL-lactic acid) fibers were prepared, and the molecular orientation was characterized by polarized Fourier-transform infrared (FT-IR) spectroscopy. For randomly deposited fibers, the parallel polarized FT-IR spectrum was the same as that of the perpendicularly polarized spectrum, indicating that there was no specific molecular orientation in this electrospun film. In contrast, for the uniaxially aligned sample, IR band intensities and the positions of C-O-C stretching changed when the IR beam was polarized either parallel or perpendicular to the fiber axis. Because the C-O-C stretching is parallel to the polymer backbone, this change indicates that the polymer chain in the fiber was stretched and aligned. The dichroic ratio of the band at 1090 cm −1 , attributed C-O-C stretching, was 2.9. Furthermore, the high-frequency shift of the peaks in its perpendicularly IR spectra suggests that the polymer chains in the fiber were tightly packed during the electrospinning process.

Hydrophilicity Affecting the Enzyme-Driven Degradation of Piezoelectric Poly-l-lactic Films

“…For our oriented PLLA films, the intensities of the C=O and C-O-C peaks are enhanced in the drawing direction (horizontal) compared to the perpendicular direction (vertical) and shifted to slightly lower values (Figure 3, right). Comparable changes in the C=O and C-O-C peaks were also observed by T. Nobeshima et al [20]. Regarding the influence of the water wettability, the orientation was decreased for both the hydrophobic non-etched and hydrophilic etched films during degradation (Table 1 and Figure 3).…”

“…Spectra were recorded in the 600–4000 cm −1 wavenumber range with a spectral resolution of 4 cm −1 and the accumulation of 10 spectra using a polarizer. Changes in the orientation were determined using the previous equation, where D represents the ratio between changes of the vertical (‖) and horizontal ( ) absorbance ( A ) of the C=O peak (1756 cm −1 ) using the following equation [ 19 , 20 ]: …”

Osteogenic differentiation of mesenchymal stem cells on random and aligned PAN/PPy nanofibrous scaffolds

“…The quantitative relationship between the preferred orientation and fiber morphology was reported in literature. 46,47 The polarized FT-IR spectra of aligned PAN/PPy nanofibers showed anisotropy, indicating that the polymer chain in the fiber was stretched and aligned in the fiber axis during electrospinning process.…”

Amorphous Electrically Actuating Submicron Fiber Waveguides

“…Although the fabricated fibers contain small amounts of R6G with a doping ratio of 7.7 × 10 −2 wt% relative to the PDLLA, a pure PDLLA fiber core is assumed to simplify the calculation model. In addition, PDLLA polymer chains can be modestly aligned to the fiber directions in electrospun PDLLA fibers, which results in both birefringence and an inhomogeneous refractive index distribution in the fiber. We assume that the PDLLA fiber has a homogeneous, isotropic refractive index distribution.…”

“…Figure 1 shows n PDLLA and n CYTOP with different wavelengths, where n PDLLA is measured from a spin-coated PDLLA film and n CYTOP is obtained from the production information of CYTOP. The plots in Figure 1 are fitted using the one-term Sellmeier formula shown in the figure. Although the refractive indices of spin-coated PDLLA films can differ from those of electrospun PDLLA fibers due to the modestly aligned PDLLA polymer chains in the fibers, [19] we used the indices of the films because of the difficulty of measuring those of small fibers. Using the fitted formulae for n PDLLA and n CYTOP , values of β are obtained with different diameters (2a) and wavelengths than those in Equation (4), as shown in Figure 2a.…”