蒙皂族粘土矿物组成和微结构影响层离性的本质和规律的研究

The complete delamination of smectite clay minerals remains a tough problem in the fundamental clay science and clay mineral-based nanotechnology. Many previous studies are primarily based on the samples of available naturally-occurring smectite clay minerals and on the screening and improvement of delamination process technology. As a result, the insight into the inherent principles and laws remains unclear. As such, the applicant proposes the present project, according to the applicant’s experience and characteristics of studies on clay minerals and the comprehensive survey on the progress of science and technology on clay minerals. The objective of the present proposal is to probe and uncover the inherent reasons and laws of the effects of the composition and the microstructure of the layer, the layer edge, and the interlayer ions on the delamination of smectitic clay minerals in water. Both natural smectitic clay mineral samples and synthetic smectitic clay mineral samples made from controlled hydrothermal reactions and intensified chemical processes will be used. In this way, the montmorillonite samples and the saponite samples will be achieved systematically. The samples will be finely analyzed and characterized to disclose the details on the composition and the structure of the octahedral sheet and the tetrahedral sheet on the layer, including the identification of the occupied central atom, the mode and the amount of isomorphous substitution, valence, geometry configuration and coordination. The ions in the interlayer space, the stacking fault and the crystallite size and their influences on the hydration and delamination of clay minerals will also be determined. The investigation aims to get comprehensive understanding and theoretic elaboration on the inherent reasons, key factors and quantified correlations between the delamination and the compositional and structural parameters related to the tetrahedral sheet, the octahedral sheet, the interlayer ions, the crystallite size and the edges, and the stacking fault. Such scientific idea and investigation have not yet been reported at home and abroad. It belongs to a multidisciplinary study involving in clay minerals, inorganic synthesis, physical chemistry and chemical engineering. The study is essential to clay science and is practically significant to the processing of clay minerals.

蒙皂族粘土矿物的充分层离是矿物学和纳米粘土技术面临的难题之一，仅依赖若干天然矿物样品研究和筛选改进层离工艺存在局限性，相关层离规律认识欠缺。因此，申请人依据自身对蒙皂族粘土矿物的研究积累、特色及国内外进展提出本项目，研究蒙皂族粘土矿物单元层中化学组成和微结构、端面化学和层间域离子影响矿物在水相中层离的本质和规律。实验从天然和人工可控合成粘土矿物相结合的新角度，采用水热反应和化工强化等技术方法获得蒙脱石和皂石等系列化试样，精细表征和对比考察八面体、四面体中心占位原子、类质同像替代方式和数量、价态和周围环境中原子几何配置等，分析层间域离子种类、数量、堆垛层错、端面与水化作用的关系，解析四面体片、八面体片、层间域离子、晶粒尺度、堆垛层错影响矿物在水相中层离的机制、关键因素和量化规律。思路和内容尚未见报道，系粘土矿物、无机合成、物理化学和化工等交叉研究，对粘土矿物学和加工有必要性和实际价值。

蒙皂族粘土矿物的充分层离是矿物学和纳米粘土技术面临的难题之一，仅依赖若干天然矿物样品研究和筛选改进层离工艺存在局限性，相关层离规律认识欠缺。本项目，研究了蒙皂族粘土矿物单元层中化学组成、微结构、端面化学、层间域离子影响矿物在水相中层离的本质和规律。实验从天然和人工可控合成粘土矿物相结合的新角度，采用水热反应和表面改性等技术方法获得了皂石、蒙脱石等系列化试样。通过精细表征和对比考察了八面体、四面体中心占位原子、类质同像替代方式和数量、价态和周围环境中原子几何配置等，分析了层间域离子种类、数量、端面与水化作用的关系，解析了四面体片、八面体片、层间域离子、晶粒尺度影响矿物在水相中层离的机制、关键因素和量化规律。结果表明，合成皂石Si/Al摩尔比为10：1至25：1时，其水分散体系能自发形成凝胶。Si/Al摩尔比越高，合成皂石的结晶度越好。将聚丙烯酸钠（NaPA）加入皂石的水分散体系中，能促进了皂石的分散，降低了粘度和触变性能，并使凝胶变成溶胶。NaPA可以在皂石颗粒的电场下瞬间极化，然后迅速进入皂石颗粒的水化层，破坏皂石凝胶的结构。当十六烷基三甲基铵阳离子的浓度为138.5 g/L，水与蒙脱石质量比为3时合成的有机蒙脱石具有更有序的“假三层”结构，其在二甲苯中的膨胀指数可达到39mL/g。非离子型芥酸酰胺（EA）或油酸酰胺（OA）均不能有效地进入蒙脱石的层间。但是，十八烷基三甲基铵阳离子（ODTMA+）与EA可以共插层蒙脱石，基面间距可增加到4.22 nm，进一步实现了蒙脱石片层的层离。ODTMA+和EA或OA共插层的有机蒙脱石在二甲苯中的膨胀度随着EA和OA负载量的增加而增大直至100%。合成皂石的NaPA调控凝胶系统和蒙脱石的共插层可用于将蒙皂族粘土矿物剥离为二维纳米片。这些实验和发现揭示了影响层离的关键参数以及调控层离性的方法，为发展工业化蒙皂族粘土矿物层离新技术路线和新改性工艺提供了实验和理论基础，同时拓宽了蒙皂族粘土在油墨、橡胶、药物传递和组织工程等领域的应用。