基于金银纳米粒子取向的高分子复合薄膜的压力敏感行为

发布时间：2018-06-13 12:28

本文选题：贵金属纳米粒子 + 局域表面等离子体共振　；参考：《哈尔滨工业大学》2016年博士论文

【摘要】：近年来,具有局域表面等离子体共振行为的贵金属纳米粒子由于在光电子学、传感、催化及光热治疗等领域具有广阔的应用前景,受到了研究者们的广泛关注。在传感领域,基于局域表面等离子体共振现象可以检测化学物质和生物分子,但是基于该现象对压力进行检测的研究目前还处于起步阶段;另外,目前传感方面的应用只局限于利用局域表面等离子体共振行为随介电环境、颗粒形貌以及组装行为的变化,而其随其他因素(如粒子取向)的变化尚未得到利用。本文基于贵金属纳米粒子的局域表面等离子体共振随取向的变化设计和制备了一种压力敏感薄膜,利用共振峰比值变化率对该高分子复合薄膜的压力敏感行为进行了评价,并对此压力敏感行为进行了数值模拟。首先利用离散偶极子近似方法模拟了棒状和片状贵金属纳米粒子在不同取向下的局域表面等离子体共振行为,并在此基础上提出了一种基于贵金属纳米粒子取向变化的压力敏感模型。贵金属纳米粒子/高分子复合薄膜受压发生形变时会导致纳米粒子从无序分布变到有序分布的状态,进而会引起其共振峰比值发生变化,从而可以利用该比值的变化测量压力的大小。利用种子生长法和热注入法合成了一系列用于构建压力敏感薄膜的贵金属纳米粒子,包括Au纳米棒、Ag纳米片、Ag@Au复合纳米片以及Au纳米颗粒。通过种子生长工艺获得了不同长径比的Au纳米棒,其长径比为2.06、2.31和2.60,其纵向共振峰分别位于651 nm、688 nm和726 nm。Ag纳米片为三角片状,边长和厚度分别为135 nm和15 nm,其面内偶极共振峰位于793 nm。Ag@Au复合纳米片的Au壳层厚度分别为3 nm、4 nm和13 nm,其面内偶极共振峰分别位于758 nm、786 nm和819 nm。采用流延法制备了压力敏感的Au纳米棒/PVA复合薄膜和Ag@Au复合纳米片/PVP复合薄膜。不同的贵金属纳米粒子在薄膜中分散良好,其局域表面等离子体共振峰由于周围介质折射率的升高均发生了一定的红移。通过分析贵金属纳米粒子/高分子复合薄膜在受压时消光光谱的变化,探讨了如何利用此变化来表征压力的大小,对不同种类的共振峰峰强的选取方法给出了定义,并进一步定义了共振峰强比值变化率。研究了压力大小、施压时间、纳米粒子形貌参数和薄膜中的PEG含量等因素对基于贵金属纳米粒子取向变化的高分子复合薄膜的压力敏感行为进行了试验研究,发现共振峰强比值变化率与外加应力的强度和作用时间有关,说明可以利用高分子形变流动引起的贵金属纳米粒子取向的变化来构建压力敏感薄膜,用来测量薄膜所受的静态压力。Au纳米棒/高分子复合薄膜和Ag@Au复合纳米片/高分子复合薄膜的测量范围分别为6.93~27.72 MPa和13.86~55.44 MPa,精度均为?8%左右。该类压力敏感薄膜的应力敏感性可以通过改变复合薄膜中塑性剂PEG的含量以及纳米粒子的长径比进行调节,用来表征压力的共振峰比值变化率会随着PEG含量的升高或Au纳米棒长径比的增加逐渐增大。从薄膜的受力分析出发可知高分子薄膜形变过程中存在的流场类型为简单平面拉伸流场,进而通过棒状粒子(或片状粒子)在流体中取向变化的理论推导出了粒子取向变化的表达式,发现粒子取向的变化与高分子的形变量以及粒子的长径比有关。通过结合贵金属纳米粒子共振峰峰强的表达式、纳米粒子在不同形变量条件下的取向变化以及共振峰比值变化率随压力和时间变化的试验结果,得出了复合薄膜形变量随压力和时间变化的关系。利用Burgers模型对形变量的变化进行拟合,得到了高分子复合薄膜的形变量表达式,进而得到了共振峰比值变化率随压力和时间变化的模拟结果。本文提出的预测模型可以较好地模拟出共振峰比值变化率随压力和时间的变化,除时间较短的情况外,误差基本都在10%以内。
[Abstract]:In recent years, precious metal nanoparticles with local surface plasmon resonance have wide application prospects in the fields of optoelectronics, sensing, catalysis and photothermal therapy, which have attracted wide attention of researchers. In the field of sensing, chemical substances and biomolecules can be detected based on the phenomenon of local surface plasmon resonance. However, the study of pressure detection based on this phenomenon is still in the initial stage. In addition, the current sensing application is limited to the changes in the local surface plasmon resonance behavior with the dielectric environment, the particle morphology and the assembly behavior, and the change with other factors (such as particle orientation) has not been used. A pressure sensitive film is designed and prepared on the local surface plasmon resonance of noble metal nanoparticles with the change of orientation. The pressure sensitive behavior of the polymer composite film is evaluated by the ratio of resonance peak ratio, and the numerical simulation of the pressure sensitive behavior is carried out. First, the discrete dipole approximation is used. The local surface plasmon resonance behavior of rod like and flake like noble metal nanoparticles under different orientations is simulated by method. On this basis, a pressure sensitive model based on the orientation change of noble metal nanoparticles is proposed. The distribution of the cloth to an ordered distribution, and then the ratio of the resonance peak, can be changed to measure the pressure by the change of the ratio. A series of noble metal nanoparticles, including Au nanorods, Ag nanoscale, Ag@Au composite nanoscale, are synthesized by the method of seed growth and heat injection. Au nanorods with different length to diameter ratio are obtained by seed growth process. The length to diameter ratio of Au nanorods is 2.06,2.31 and 2.60. The longitudinal resonance peaks are at 651 nm, 688 nm and 726 nm.Ag nanoscale are triangular flaky, and the border length and thickness are 135 nm and 15 nm respectively. The internal polar resonance peak is located in the Au shell of 793 nm.Ag@Au composite nanoscale. The thickness of the layer is 3 nm, 4 nm and 13 nm respectively. The dipole resonance peaks in the surface are located at 758 nm, 786 nm and 819 nm., respectively. The pressure sensitive Au nanorod /PVA composite film and the Ag@Au composite nanoscale /PVP composite film are prepared. The increase of the refractive index of the surrounding medium has a certain red shift. By analyzing the change of the extinction spectrum of the noble metal nanoparticles / polymer composite films at compression, this paper discusses how to use this change to characterize the size of the pressure, and defines the selection method of different kinds of peak intensity of the resonance peak, and further defines the resonance peak strength. The ratio variation rate. The pressure sensitivity of the polymer composite film based on the orientation change of the noble metal nanoparticles was studied by the pressure size, the pressure time, the morphology parameters of the nanoparticles and the PEG content in the film. It was found that the ratio of the ratio of the resonance peak strength was related to the strength and time of the applied stress. It is clear that the pressure sensitive film can be constructed by the change of the orientation of the noble metal nanoparticles caused by the deformation of the polymer. The measurement of the static pressure.Au Nanorods / polymer composite films and the Ag@Au composite nanoscale / polymer composite films are 6.93~27.72 MPa and 13.86~55.44 MPa respectively. The precision is 8%? The stress sensitivity of this kind of pressure sensitive film can be adjusted by changing the content of the plastic agent PEG in the composite film and the length to diameter ratio of the nanoparticles. It is used to indicate that the ratio of the resonance peak ratio of the pressure increases with the increase of the content of PEG or the increase of the length to diameter ratio of the Au nanorods. The flow field in the process of polymer film deformation is simple plane stretch flow field, and then the expression of particle orientation change is derived through the theory of orientation change of rod like particles (or flaky particles) in the fluid. It is found that the change of particle orientation is related to the shape variable of polymer and the length to diameter ratio of the particles. The expression of the peak peak intensity of the nanoparticles, the orientation change of the nanoparticles under different shape variables and the experimental results of the change rate of the ratio of the resonance peak to the pressure and time are obtained. The relationship between the change of the composite film shape variable with the pressure and the time is obtained. The change of the shape variable is fitted by the Burgers model, and the polymer is obtained. The shape variable expression of the composite film is obtained, and the simulation results of the variation rate of the resonance peak ratio with the pressure and time are obtained. The prediction model proposed in this paper can well simulate the change rate of the resonance peak ratio with the pressure and time, and the error difference is basically within 10% except the short time.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TB383.2

【相似文献】