Large-Scale Fabrication of Bioinspired Fibers for Directional Water Collection
Large-Scale Fabrication of Bioinspired Fibers for Directional Water Collection
复制标题
大规模制造用于定向集水的仿生纤维
DOI：
10.1002/smll.201101408
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发表时间：
2011-12-16
期刊：
影响因子：
13.3
通讯作者：
Jiang, Lei
中科院分区：
文献类型：
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作者：
Bai, Hao;Sun, Ruize;Jiang, Lei
图1a示出了制造设置的示意图。将尼龙纤维（参见图S1，支持信息（SI））水平送入聚合物溶液的储液器，以避免重力引起的液体流动。在溶液容器的壁上，使用两个毛细管（内径约400 μm）来引导光纤。当纤维被马达稳定地从容器中拉出时，它被聚合物溶液涂覆。制造过程由电荷耦合器件（CCD）相机原位记录。在尼龙纤维上大规模地具有聚（甲基丙烯酸甲酯）（PMMA）纺锤结的所制备的生物启发纤维示于图1 B、c中。在每根纤维上可以很容易地发现周期性的纺锤结（纯白色）（图1c）。扫描电子显微镜（SEM）用于观察所制备的纤维的详细结构。图1d中的SEM图像显示了一个典型的纺锤结，高度为173.3 μm，长度为1514.3 μm。图1 e、f中的放大SEM图像分别显示了轴结中部和侧面区域的随机和拉伸多孔结构。这些研究表明，具有与天然蜘蛛丝类似结构的生物启发纤维[3]可以大规模成功制造。为了更详细地研究生物启发纤维的制造过程，我们首先关注在毛细管末端发生的流体涂覆过程，如图2a-d所示。聚合物溶液由溶解在N，N-二甲基甲酰胺（DMF）中的PMMA组成，重量百分比为11%。拉伸前，尼龙纤维通过毛细管中心水平固定（图2 a）。纤维直径约为75 μm，没有聚合物溶液沉积。当电机以1.321 mm s-1的速度将光纤连续拉出溶液容器时，形成溶液的动态弯月面（图2 B中的箭头）。在距毛细管端部一定距离内（φ 2.67 mm），光纤均匀地涂有厚度为φ 53.8 μm的溶液膜，如图2 c所示。我们知道，由于瑞利不稳定性，这种圆柱形液膜在超过临界长度时通常是不稳定的。[24]为了进一步研究纺锤结的形成机理，我们使用CCD相机原位观察膜破裂过程。首先，尼龙纤维均匀地涂上PMMA膜（厚度为53.8 μm，见图2 e）。在短时间（约0.28 s）后，观察到溶液膜不稳定（图2 f）。如图2g中的箭头所示，膜厚度在某些区域中变厚。以来
Figure 1a shows a schematic of the fabrication setup. A nylon fiber (see Figure S1, Supporting Information (SI)) is horizontally fed through a reservoir of polymer solution in order to avoid gravity-induced liquid flow. On the walls of the solution container, two capillary tubes (≈ 400 μm inner diameter) are used to guide the fiber. When the fiber is steadily drawn out of the reservoir by a motor it is coated with the polymer solution. The fabrication process is recorded in situ by a charge coupled device (CCD) camera. The as-prepared bioinspired fibers with poly (methyl methacrylate)(PMMA) spindle-knots on nylon fibers on a large scale are shown in Figure 1 b, c. Periodic spindle-knots (pure white color) can be easily found on each fiber (Figure 1 c). Scanning electron microscopy (SEM) is used to observe the detailed structure of the as-prepared fiber. The SEM image in Figure 1 d shows a typical spindle-knot with height of≈ 173.3 μm and length of≈ 514.3 μm. The magnified SEM images in Figure 1 e, f show the random and stretched porous structure on the middle and side regions of the spindle-knot, respectively. These investigations demonstrate that bioinspired fibers with a similar structure to natural spider silk [3] can be successfully fabricated on a large scale. In order to investigate in more detail the fabrication process of the bioinspired fibers we firstly focused on the fluid-coating process that occurs at the end of the capillary tube, as shown in Figure 2a–d. The polymer solution is composed of PMMA dissolving in N, N-dimethylformamide (DMF) with a weight percentage of 11%. Before stretching, the nylon fiber is fixed horizontally through the center of the capillary tube (Figure 2 a). The fiber is about 75 μm in diameter and no polymer solution is deposited. When the fiber is continuously drawn out of the solution reservoir by the motor at a velocity of≈ 3.21 mm s− 1, the dynamic meniscus of the solution is formed (arrow in Figure 2 b). Within a certain distance from the end of the capillary tube (≈ 2.67 mm), the fiber is uniformly coated with a solution film thickness of≈ 53.8 μm, as shown in Figure 2 c. As we know, such a cylindrical liquid film is generally unstable when it exceeds a critical length owing to the Rayleigh instability.[24] As can be seen in Figure 2 d, a spindle-knot shape polymer droplet is found. To further investigate the formation mechanism of spindleknots we observe the film break-up process in situ using a CCD camera. At first, the nylon fiber is uniformly coated with the PMMA film (≈ 53.8 μm thick, see Figure 2 e). After a short while (≈ 0.28 s), the film of solution is observed to be unstable (Figure 2 f). The film thickness grows thicker in some regions, as indicated by the arrows in Figure 2 g. Since the