The recent introduction of nanoclays as fillers or additives in polymers for various desired effects is a subject of an increased interest for research and development to establish various applications. An increased consumption is indicated by the wider applications of clay nanocomposites approaching to almost one-quarter (24 pct) in 2005 of the total nanocomposites used. However, an interesting concern, along with the studies addressing how nanoclays change the behavior of polymeric materials, is to discover what are clays, nanoclays and montmorillonite minerals. The various structures of montmorillonite available in nature and their modification for application are discussed. An attempt is made to review the origin of using clays when nanotechnology did not exist, coupled with the effects of montmorillonite-based nanoclays on commercially known polymers.

Clay mineral is an important material available in nature. With an increasing understanding of clay structure, montmorillonite is realized viable for an enhanced performance in a variety of materials and products in the areas of catalysis, food additive, antibacterial function, polymer, sorbent, etc. Significant development in the use and application of montmorillonite is seen in recent time. This chapter provides an overview of montmorillonite, structure, and properties and particularly discusses its recent utilization in important materials. Montmorillonite is introduced in terms of its natural sources, chemical structure, physical and chemical properties, and functional utilization. The important physical and chemical properties are summarized as particle and layered structure, molecular structure and cation exchange effect, barrier property, and water sorption. This is followed by the important functional utilizations of montmorillonite based on the effects of its chemical structure. The important functional utilization of montmorillonite includes food additive for health and stamina, for antibacterial activity against tooth and gum decay, as sorbent for nonionic, anionic, and cationic dyes, and the use as catalyst in organic synthesis. The environment concerns, to date, do not indicate the adversity for particles used as additive. Studies will be useful which are clearly based on any montmorillonite structure to describe environmental effects.A common characteristic of clay mineral is a fine-grained natural structure in a sheet-like geometry. The sheet-structured hydrous silicates are generally called phyllosilicates [3]. The natural clay particle is smaller than 0.004 mm in diameter that may range from 0.002 to 0.001 mm for quartz, mica, feldspar, iron, and aluminum oxides [4]. Colloidal clay particles are finer and found in layered silicates (<0.001 mm in diameter).Clay minerals may be grouped in four types, shown in Table 1. The group members vary mainly in the layered structure. These include the kaolinite group, the smectite group (montmorillonite group), the illite group, and the chlorite group [5].The kaolinite group has three members including kaolinite, dickite, and nacrite; the formula for kaolinite group is Al 2 Si 2 O 5 (OH) 4 .The illite group is represented by mineral illite, the only common clay type. The general formula for illite is (K, H)Al 2 (Si, Al) 4 O 10 (OH) 2 ⋅ XH 2 O. It is an important rock-forming mineral and main component of shales. The structure of this group is similar to the montmorillonite group with silicate layers sandwiching an aluminum oxide/hydroxide layer in the same stacking sequence.The chlorite group is relatively large. This group is not necessarily considered as part of clays; therefore, it is placed as a separate group in phyllosilicate. The members in chlorite group are mesite, chamosite, cookeite, and daphnite with varying formulas and structures. There is no general formula.The variety of clay minerals is based on the arrangement of tetrahedral and octahedral s...

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Recent developments in nanoscience have appreciably modified how diseases are prevented, diagnosed, and treated. Metal nanoparticles, specifically silver nanoparticles (AgNPs), are widely used in bioscience. From time to time, various synthetic methods for the synthesis of AgNPs are reported, i.e., physical, chemical, and photochemical ones. However, among these, most are expensive and not eco-friendly. The physicochemical parameters such as temperature, use of a dispersing agent, surfactant, and others greatly influence the quality and quantity of the synthesized NPs and ultimately affect the material’s properties. Scientists worldwide are trying to synthesize NPs and are devising methods that are easy to apply, eco-friendly, and economical. Among such strategies is the biogenic method, where plants are used as the source of reducing and capping agents. In this review, we intend to debate different strategies of AgNP synthesis. Although, different preparation strategies are in use to synthesize AgNPs such as electron irradiation, optical device ablation, chemical reduction, organic procedures, and photochemical methods. However, biogenic processes are preferably used, as they are environment-friendly and economical. The review covers a comprehensive discussion on the biological activities of AgNPs, such as antimicrobial, anticancer anti-inflammatory, and anti-angiogenic potentials of AgNPs. The use of AgNPs in water treatment and disinfection has also been discussed in detail.

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