Clay/nanocomposite hydrogels: In review

Abstract

The development of advanced materials those are stronger, more rigid, lighter, hotter and self-renewable than existing materials has been the rising point of many research studies conducted in recent years. Within this scope, the interest to production of nanostructured materials is received considerable attention worldwide due to their potential positive contribution to wide variety of technological areas such as electronics, catalysis, adsorbents, ceramics, magnetic data storage, structural components etc. In these efforts polymer nanocomposites as the form of hydrogels, reinforced with well-dispersed layered silicate, typically montmorillonite can be given as a one of the promising composite material. However, long-standing problems for polymer-clay nanocomposites include actual exfoliation of clay particles in discrete layers, uniform distribution of clay layers throughout the polymer, and randomness of clay sequences. For the exfoliation of clay particles, although the chemical modification of clay minerals in aqueous media is the well-known and more general way applied by researchers, the physical pathway method performed by high-energy ball mills is also gaining increasing attention as an alternative pretreatment way. Grinding of crushed materials is one of the key processes in the mineral and cement industry, but the increased concern on the preparation of fine-grained powders (nano powders) or the manufacture of composites with desirable properties, especially performed with use of high-energy ball mills, has led to significantly widen the usage field of grinding. Undoubtedly, the main reason for these efforts is to improve the performance of existing materials. In this paper the fundamental concepts, classification, physical and chemical characteristics and the production methods of clay/polymer nanocomposites was briefly reviewed base on the composite hydrogel. Particular attention was paid to the pre-treatment (exfoliation) of clays with high-energy ball mills, which is increasingly being accepted as an alternative method to eliminate the negative effects of chemical treatment in some composite forms.