纤维素纳米晶基功能复合材料的制备与应用研究
发布时间：2018-10-26 17:42
【摘要】：本文采用真空抽滤的方法,并通过控制不同的条件制备了具有一系列不同颜色的纤维素纳米晶基彩色膜,并借助扫描电镜(SEM),原子力显微镜(AFM),红外(IR), X-ray衍射(XRD),圆二色谱(CD)等表征手段对彩色膜的内部结构进行了研究,并探索了复合膜其它的性能。通过对硫酸酸解纤维素的制备条件的探索,我们分别制备了针尖状的微晶纤维素纳米晶和棉浆纤维素的纳米晶,发现棉浆纤维素纳米晶的平均粒径比微晶纤维素纳米晶的平均粒径要稍微大些。然后将纳米晶溶液真空抽滤成膜后,表征了膜的热性能和内部结构,酸解前后纤维素的晶型不会发生变化,但是由于酸解过程中接上了磺酸根基团使得热稳定性降低。我们对纤维素纳米晶溶液进行短时间超声和长时间超声后得到了纤维素纳米晶的无色膜和彩色膜,这种彩色膜面积大、表面光滑平整、透明性好、无裂纹,而且膜的颜色随着入射光角度的不同而发生变化。通过SEM对其垂直断面和斜截面进行表征,发现彩色膜内纤维素纳米棒是手性向列相螺旋结构,又借助CD曲线证实是左手行结构,因此膜具有彩色。还通过控制超声时间、纤维素纳米晶悬浮液的体积和真空度制备了一系列不同颜色和不同厚度的彩色膜。我们还设计了两种不同的路线制备了氧化石墨烯(GO)/纤维素纳米晶(CNC)的杂化膜,研究了第二组份GO与CNC相容性的不同对得到的CNC膜颜色和性能的影响。实验证明,和CNC形成稳态溶液制备的GO/CNC膜是无彩色的,而和CNC形成亚稳态溶液体系制备的GO/CNC膜是有彩色的。将GO/CNC杂化膜化学还原后,GO/CNC彩色膜内的有序结构没被破坏,在还原后依然是具有彩色的。而且这两种膜展现出良好的导电性。鉴于以上的工作,我们又将具有导电性的二维片层石墨烯(TRG)与一维的纤维素纳米晶复合后得到了一种具有金属光泽的彩色膜,我们改变超声时间和TRG的含量制备了不同颜色的TRG/CNC彩色膜。这些膜不仅具有导电性,而且我们发现这些彩色膜对水分具有非常强烈的响应性。我们从膜的结构上对这种水响应性进行了研究,认为TRG的加入不仅改变了纤维素纳米棒的液晶结构的螺距,而且TRG还起到染色剂的作用吸收水分,因而使得TRG/CNC复合膜对水具有极强烈的响应性。
[Abstract]:Cellulose nanocrystalline color films with a series of different colors were prepared by vacuum filtration method and controlled under different conditions. Scanning electron microscope (SEM), atomic force microscope (AFM),) and infrared (IR), (IR) were used to prepare the color films. The internal structure of the color film was studied by X-ray diffraction (XRD), circular dichroism (CD) and other properties of the composite film were explored. By exploring the preparation conditions of sulfuric acidolysis cellulose, we have prepared apical microcrystalline cellulose nanocrystals and cotton pulp cellulose nanocrystals, respectively. It is found that the average particle size of cellulose nanocrystals in cotton pulp is slightly larger than that of microcrystalline cellulose nanocrystals. After vacuum filtration of nanocrystalline solution, the thermal properties and internal structure of the membrane were characterized. The crystalline form of cellulose did not change before and after acidolysis, but the thermal stability was decreased due to the addition of sulfonic acid group in the process of acidolysis. We get colorless and color films of cellulose nanocrystals after short and long time ultrasound. The color films have large area, smooth and smooth surface, good transparency and no cracks. And the color of the film varies with the angle of incident light. The vertical and oblique sections were characterized by SEM. It was found that the cellulose nanorods in the color film were chiral nematic helical structure and proved to be left-handed by means of CD curve, so the film had color. A series of color films with different color and thickness were prepared by controlling ultrasonic time, volume and vacuum degree of cellulose nanocrystalline suspension. We also designed two different routes to prepare hybrid membranes of graphene oxide (GO) / cellulose nanocrystalline (CNC). The effects of the compatibility of the second component GO and CNC on the color and properties of CNC films were studied. The experimental results show that the GO/CNC films prepared by the steady-state solution formed with CNC are colorless, while the GO/CNC films prepared by the metastable solution system formed by CNC are colourful. After the chemical reduction of GO/CNC hybrid film, the ordered structure of GO/CNC color film was not destroyed and was still colored after reduction. Moreover, the two films exhibit good electrical conductivity. In view of the above work, a color film with metallic gloss was obtained by combining the electrically conductive two-dimensional graphene (TRG) with one-dimensional cellulose nanocrystals. We prepared different color TRG/CNC color films by changing ultrasonic time and TRG content. These films are not only electrically conductive, but also highly responsive to water. We studied the structure of the membrane and found that the addition of TRG not only changed the pitch of the liquid crystal structure of cellulose nanorods, but also played the role of dyeing agent to absorb water. Therefore, the TRG/CNC composite membrane is highly responsive to water.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332
[Abstract]:Cellulose nanocrystalline color films with a series of different colors were prepared by vacuum filtration method and controlled under different conditions. Scanning electron microscope (SEM), atomic force microscope (AFM),) and infrared (IR), (IR) were used to prepare the color films. The internal structure of the color film was studied by X-ray diffraction (XRD), circular dichroism (CD) and other properties of the composite film were explored. By exploring the preparation conditions of sulfuric acidolysis cellulose, we have prepared apical microcrystalline cellulose nanocrystals and cotton pulp cellulose nanocrystals, respectively. It is found that the average particle size of cellulose nanocrystals in cotton pulp is slightly larger than that of microcrystalline cellulose nanocrystals. After vacuum filtration of nanocrystalline solution, the thermal properties and internal structure of the membrane were characterized. The crystalline form of cellulose did not change before and after acidolysis, but the thermal stability was decreased due to the addition of sulfonic acid group in the process of acidolysis. We get colorless and color films of cellulose nanocrystals after short and long time ultrasound. The color films have large area, smooth and smooth surface, good transparency and no cracks. And the color of the film varies with the angle of incident light. The vertical and oblique sections were characterized by SEM. It was found that the cellulose nanorods in the color film were chiral nematic helical structure and proved to be left-handed by means of CD curve, so the film had color. A series of color films with different color and thickness were prepared by controlling ultrasonic time, volume and vacuum degree of cellulose nanocrystalline suspension. We also designed two different routes to prepare hybrid membranes of graphene oxide (GO) / cellulose nanocrystalline (CNC). The effects of the compatibility of the second component GO and CNC on the color and properties of CNC films were studied. The experimental results show that the GO/CNC films prepared by the steady-state solution formed with CNC are colorless, while the GO/CNC films prepared by the metastable solution system formed by CNC are colourful. After the chemical reduction of GO/CNC hybrid film, the ordered structure of GO/CNC color film was not destroyed and was still colored after reduction. Moreover, the two films exhibit good electrical conductivity. In view of the above work, a color film with metallic gloss was obtained by combining the electrically conductive two-dimensional graphene (TRG) with one-dimensional cellulose nanocrystals. We prepared different color TRG/CNC color films by changing ultrasonic time and TRG content. These films are not only electrically conductive, but also highly responsive to water. We studied the structure of the membrane and found that the addition of TRG not only changed the pitch of the liquid crystal structure of cellulose nanorods, but also played the role of dyeing agent to absorb water. Therefore, the TRG/CNC composite membrane is highly responsive to water.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332
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