Polarized FT-IR study of macroscopically oriented electrospun nylon-6 nanofibers
Polarized FT-IR study of macroscopically oriented electrospun nylon-6 nanofibers
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DOI：
10.1021/ma701927w
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发表时间：
2008-02-26
期刊：
影响因子：
5.5
通讯作者：
Rabolt, John F.
中科院分区：
文献类型：
--
作者：
Lee, Keun-Hyung;Kim, Kwan-Woo;Rabolt, John F.
采用线速度为0 ~ 900 m/min的旋转捕集器制备了随机沉积或部分排列的静电纺尼龙-6纳米纤维，并用偏振傅里叶变换红外（FT-IR）光谱对其分子取向进行了表征。在线速度为0 m/min时，由于带电射流的弯曲不稳定性，静电纺尼龙-6纳米纤维被随机沉积到集热器上。在这种情况下，平行极化FT-IR光谱（在两个相互垂直的方向上获得）与垂直极化光谱相同，表明电双色膜中不存在分子取向。当集热器的线速度从0增加到300 m/min时，观察到红外波段强度的变化，包括在3303 cm（-1）处的NH拉伸带和酰胺I和酰胺II振动（分别为1647和1543 cm(-1)）。同时，在平行极化的FT-IR光谱中，随着集热器线速度的增加，酰胺II的振动强度逐渐增加，而在垂直极化的光谱中，酰胺II的振动强度则逐渐降低。这表明聚合物链优先沿纤维轴取向。此外，在SEM显微图中观察到纤维的平均直径减小（从250 nm到125 nm），表明纤维被高速旋转收集器拉伸和排列。
Randomly deposited or partially aligned electrospun nylon-6 nanofibers were prepared by using a rotating collector with linear velocity from 0 to 900 m/min, and their molecular orientation was characterized with polarized Fourier-transform infrared (FT-IR) spectroscopy. At a linear velocity of 0 m/min, electrospun nylon-6 nanofibers are randomly deposited onto a collector owing to the bending instability of the charged jet. In this case the parallel polarized FT-IR spectrum (obtained at two mutually perpendicular directions) is the same as the perpendicular polarized spectrum, indicating that there is no molecular orientation in the electropun membrane. When the linear velocity of the collector was increased from 0 to 300 m/min, several changes in IR band intensity are observed, including the NH stretching band at 3303 cm(-1) and the amide I and II vibrations (1647 and 1543 cm(-1), respectively) in the two polarized FTIR spectra. Also, the intensity of the amide II vibration is observed to gradually increase in the parallel polarized FT-IR spectrum, with an increase in the linear velocity of the collector, whereas its intensity is observed to decrease in the perpendicularly polarized spectrum. This indicates that the polymer chains are preferentially oriented along the fiber axis. Also, a decrease in the average fiber diameter (from 250 to 125 nm) is observed in SEM micrographs, indicating that the fibers are stretched and aligned by the high-speed rotating collector.