磷酸锆碟片液晶相行为研究

发布时间：2018-04-17 10:14

本文选题：碟状胶体 + 磷酸锆　；参考：《广东工业大学》2015年硕士论文

【摘要】：在自然界和工业产品中,我们经常碰到各种碟状胶体悬浮液体系,例如粘土、沥青、红细胞以及碟状液晶太阳能电池。尽管他们在自然界中含量丰富,并且在工业上已经得到广泛地应用,但是相对球状、棒状胶体颗粒,由于模型体系的缺乏,人们对碟状胶体颗粒的研究较少。在本课题研究中,我们将以厚度均一,直径大小可控的单层ZrP碟片为模板体系,研究碟状胶体液晶的相行为。具体工作如下：1.采用水热法制备结晶态的a-ZrP碟片,并利用TBAOH将其剥离成单层ZrP碟状胶体液晶,研究了温度对碟状液晶相行为的影响。结果表明：随着温度的升高,碟状液晶的I-N相变初始临界浓φl会增大,同时I-N相变区间变宽。分析认为,对于带电的ZrP胶体悬浮液体系,ε,T随着温度的上升而减小,导致N相的融化,最终使φl;同时在更高的温度时,碟状液晶的相变对多分散性更为敏感,导致碟状液晶的I-N相变区间变宽。2.采用水热法和回流法制备不同直径大小的ZrP碟片,并利用I-N相变分离法控制碟片的多分散性,绘制了不同直径大小的ZrP碟状液晶的I-N相变相图,观察了碟片直径大小对碟状液晶I-N相变相分离速率的影响。结果发现,I-N相变临界浓度φ1会随着碟片直径的增加而变小；I-N相变速率会随着碟片粒径的减小而变大。这是因为,大的碟片更容易取向,因此大粒径的碟状液晶会率先在较低浓度进行I-N相变；而对于较小的碟片,由于其布朗运动速率较快,使其能更快地形成有序结构,因此其I-N相分离速度也就越快。3.利用TBACl分子改变碟状液晶的离子强度,研究了离子强度对液晶相行为的影响。研究发现,相变临界浓度φl随着离子浓度的增加先变大而后减小；随着离子强度的增加,碟状液晶的I-N相分离速率变快。这是因为,随着离子强度的增加,碟片的有效体积会减小,同时颗粒之间的相互静电排斥力减小。在碟状液晶的I-N相变过程中,碟片有效体积的减小会抑制N相的形成,而碟片静电作用力的减小会加强碟片各向异性从而促进N相的形成。在悬浮液的离子强度较小时,碟片有效体积的减小对液晶相变的影响起主导作用,抑制了N相的形成,φ1变大；而当悬浮液的离子强度到达一定值时,碟片静电相互作用力的减小在相变过程中取到决定性作用,促进的N相的形成,φ1减小；碟片有效体积的减小使得碟片的移动速率加快,因此I-N相分离速率变快。
[Abstract]:In natural and industrial products, we often encounter a variety of disk colloid suspension systems, such as clay, asphalt, red blood cells and disk liquid crystal solar cells.Although they are abundant in nature and have been widely used in industry, there are few researches on the disc colloidal particles due to the lack of model system.In this study, we will study the phase behavior of the disc colloidal liquid crystal using monolayer ZrP disk with uniform thickness and controllable diameter as template system.The work is as follows: 1.The crystalline a-ZrP discs were prepared by hydrothermal method, and then separated into a monolayer ZrP disc colloidal liquid crystal by TBAOH. The effect of temperature on the behavior of the disc liquid crystal was studied.The results show that with the increase of temperature, the initial critical concentration 蠁 _ l of the I-N phase transition of the disk liquid crystal increases, and the I-N phase transition range becomes wider.It is concluded that 蔚 T decreases with the increase of temperature for charged ZrP colloid suspensions, which leads to the melting of N phase and finally to 蠁 _ 1. At the same time, the phase transition of disc liquid crystals is more sensitive to the polydispersity at higher temperatures.The I-N phase transition range of the disk liquid crystal becomes wider. 2.ZrP discs with different diameters were prepared by hydrothermal method and reflux method. The polydispersity of disks was controlled by I-N phase transformation separation method. The I-N phase transition phase diagrams of ZrP disk-like liquid crystals with different diameters were plotted.The effect of disc diameter on the phase transition rate of I-N phase transition in a disc liquid crystal was investigated.The results show that the critical concentration of I-N phase transition 蠁 1 decreases with the increase of disc diameter and the change rate of I-N phase transition increases with the decrease of disc diameter.This is because large disks tend to orientate more easily, so large size disks take the lead in the I-N phase transition at lower concentrations; for smaller disks, because of their faster Brownian motion rates, they can form ordered structures faster.Therefore, the faster the I-N phase separation rate is. 3.The effect of ionic strength on liquid crystal phase behavior was studied by changing the ionic strength of disk liquid crystal with TBACl molecule.It is found that the critical concentration of phase transition 蠁 _ l increases first and then decreases with the increase of ion concentration, and the separation rate of I-N phase increases with the increase of ionic strength.This is because, with the increase of ionic strength, the effective volume of the disc decreases and the mutual electrostatic repulsive force between the particles decreases.During the I-N phase transition of the disc liquid crystal, the reduction of the effective volume of the disc will inhibit the formation of the N phase, while the decrease of the electrostatic force of the disc will enhance the anisotropy of the disc and promote the formation of the N phase.When the ionic strength of the suspension is small, the decrease of the effective volume of the disk plays a leading role in the phase transition of liquid crystal, which inhibits the formation of the N phase and increases 蠁 1, but when the ionic strength of the suspension reaches a certain value,The decrease of electrostatic interaction force plays a decisive role in the phase transition process, which promotes the formation of the N phase and the decrease of 蠁 1, and the decrease of the effective volume of the disc accelerates the moving rate of the disc, so the I-N phase separation rate becomes faster.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ134.12

【共引文献】