磁场诱导下形成的介稳态光子晶体

发布时间：2018-01-28 03:05

  本文关键词： 介稳态胶体晶 磁诱导组装 组装与解组装 微弱刺激响应　出处：《华东师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：胶体晶是以胶体颗粒作为结构基元并遵循一定的空间对称性堆积出的一维,二维或三维有序结构。在过去的研究中,人们更多关注处在稳定状态的胶体晶结构,然而对"介稳态胶体晶"的结构、特性和应用却鲜有报道。缺乏有效可控的介稳态胶体晶制备方法,缺少高度重现的研究对象,是相关研究进展缓慢的主要原因,然而不可否认的是,深入理解介稳态胶体晶对胶体组装具有重要的科学意义。也因此,介稳态胶体晶的相关研究目前正面临重大的机遇和挑战。本论文采用磁诱导的方式将Fe304磁流体中的聚苯乙烯非磁颗粒在磁场下进行组装,以获得具有介稳态特性的胶体晶。通过TEM,XRD,TGA,SEM,VSM,PH值,表面电势测定,电泳等测试技术来表征聚苯乙烯胶粒和Fe304纳米颗粒的磁响应性,表面电荷,胶粒稳定性等组装相关性质。通过实验和优化,我们得到单分散的,粒径均匀,有良好稳定性的胶体颗粒,完全满足磁场条件下组装的需求。在由体积分数为25%的聚苯乙烯胶粒和体积分数为3%的磁流体Fe304的组装体系中,非磁颗粒在外磁场作用下会产生与其所置换的磁流体相反的磁矩。因此,当施加磁场时,体系的聚苯乙烯倾向于向远离磁场的方向富集,从而会导致液体上方的非磁颗粒过饱和而形成介稳态胶体晶。这种利用磁组装形成介稳态胶体晶的方法相较于蒸发浓缩的方法具有耗时短,过程可逆,制备方便等优势,同时还能够对外界的干扰和变化产生响应。为了进一步探究磁诱导的介稳态组装与典型磁组装的区别,本论文设计了磁流体中高体积分数和低体积分数聚苯乙烯胶体晶这两种组装体系。通过显微镜观察,反射光谱等分析手段,探究组装与解组装的行为。实验结果证明,高体积分数的聚苯乙烯胶体晶是由磁场诱导形成的介稳态胶体晶,具有组装时间较长,容易解组装的特性;而低体积分数的聚苯乙烯胶体晶是传统磁组装的胶体晶,具有瞬时组装和解组装后瞬时恢复的特性,但不易受外界干扰的特性。
[Abstract]:Colloidal crystal is a kind of one-dimensional, two-dimensional or three-dimensional ordered structure, which is formed by colloidal particles as the structural unit and follows a certain spatial symmetry. In the past studies, more attention has been paid to the colloidal crystal structure in a stable state. However, there are few reports on the structure, properties and applications of the "metastable colloidal crystal". There is no effective and controllable preparation method for the meso-stable colloidal crystal and a highly reproducible object of study. Is the main reason for the slow development of the related research, however, it is undeniable that it is of great scientific significance to further understand the meso-stable colloid crystal for colloid assembly. At present, the study of mesostable colloidal crystals is facing great opportunities and challenges. In this paper, the polystyrene nonmagnetic particles in Fe304 magnetofluids are assembled in magnetic field by magnetic induction. In order to obtain the colloidal crystal with steady dielectric property, the PH value of SEMS-VSMV was determined by TEMX XRDX TGASMA VSMH, and the surface potential was determined. Electrophoretic techniques were used to characterize the magnetic response, surface charge and stability of polystyrene and Fe304 nanoparticles. Through experiments and optimization, we obtained monodisperse. The colloidal particles with uniform particle size and good stability. In the assembly system composed of polystyrene particles with volume fraction of 25% and magnetohydrodynamic Fe304 with volume fraction of 3%. When the magnetic field is applied, the polystyrene of the system tends to enrich away from the magnetic field. This method can lead to the supersaturation of the nonmagnetic particles over the liquid and form the metastable colloidal crystal. The method of using magnetic assembly to form the metastable colloidal crystal is less time-consuming and reversible than the method of evaporation and concentration. At the same time, it can respond to external interference and change. In order to further explore the difference between magnetically induced mesostatic assembly and typical magnetic assembly. In this paper, two kinds of assembly systems, high volume fraction and low volume fraction polystyrene colloid crystal in magnetofluid, were designed and analyzed by microscope and reflectance spectroscopy. The experimental results show that polystyrene colloidal crystal with high volume fraction is a kind of metastable colloidal crystal induced by magnetic field, which has the characteristics of long assembling time and easy to unassemble. The low volume fraction polystyrene colloid crystal is the traditional magnetic assembly colloid crystal, which has the characteristics of instantaneous assembly and recovery, but not easily disturbed by the outside world.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O734
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本文编号：1469589