Over the last fifteen years, increased knowledge about the science of materials and their organization has kept researchers scrambling to keep up with an ever increasing demand for engineered materials of higher and higher specifications. Nanotechnology and the incorporation of clay–polymer composite materials are ushering in a new age of materials with an impact on society that cannot be underestimated. Clay–polymer composite materials, exemplified by layered nacre-like composites as well as other similar biomimetic materials, can resolve numerous problems in the areas of energy production and storage, electronics and sensors, and medicine, to name a few. The industrial impact of many nanoclay composites, especially as a reinforcement component of common plastics, has already been realized. As one example of that, the global nanoclay market size is estimated to have exceeded $800 million in 2014. At the same time, we see only a fraction of the potential impact of nanoscale clay materials, as evidenced by many chapters in this book. One could expect that future advances in the use of nanoclay composites in self-healing materials, nanoscale sensors, cardiovascular stents, tissue engineering, neural–electronic interfaces, information-nano–bio integration, and nano-information biological-cognitive systems could radically change the lives of humankind.

The central goal of this fascinating research effort is to discover how to create materials that combine the requisite properties, including both mechanical (that is, strength, stiffness, and toughness) with so called functional properties (such as transparency, corrosion resilience, flame retardancy, etc). However, only recently has it been understood how such composites can be prepared with control of the nanoscale organization. The design of organized clay–polymeric nanocomposites demands not just exfoliation but well defined clay nanoparticles. An important role in composite processes belongs not only to the material composition, but also to the clay particle shape and size as well. Clay nanoparticles have been used to prepare sheets as thin as 1 nm and a few hundred nm wide (such as kaolin and montmorillonite), and their organized multilayers made them very strong and non-gas-permeable. Recently, an important development was reached for elongated tubule and fibrous clay particles such as halloysite, imogolite, sepiolite, and others, and this book is concerned mostly with these clay types. With natural availability, abundant deposits, low-cost, simple purification, and fibrous or hollow tubular nanostructures, clay nanocomposites have distinct advantages over synthetic nanomaterials like carbon or metal oxide nanotubes.

Halloysite tubule nanoclays represent an emerging type of nanomaterial with functional properties comparable to carbon nanotubes but are considerably less expensive. Their applied use began in high performance ceramics, as reinforcements for polymers, controlled release of active agents for composites with flame-retardant, anticorrosion, antimicrobial, and antioxidant properties. Their applications have broadened into biological areas including biomimetic materials such as bone cements and dentist formulation tissue scaffolds. Drug delivery systems, cosmetics, catalyst immobilization, specific adsorbents, and mesoporous materials for water purification can also be made from nanoclays, as exemplified by the multiple studies described in this book. Fibrous clays provided significant reinforcement properties to nanocomposites, and when assembled with biopolymers and other green polymers, they gave rise to functional bio nanocomposites. Recent findings in fabrication of drug delivery vehicles and tissue engineering constructs are highlighted. Amazing examples of interfacing biological entities (cells, tissues, DNA) with nanoclay particles are presented here as well.

In this book you will find contributions about biomedical composites, including nanosafety characterization, described in Chapters 12–14. Overall, it appears that nanoclays are safe and biocompatible nanomaterials. Notable advancements in functional substance-loaded halloysite for fibers (Chapter 1) and rubbers (Chapters 3 and 11), flame retardancy (Chapter 9), ultrafiltration and proton exchange membranes (Chapter 10), and immobilized biomacromolecules (Chapter 12) have been collected. This book also includes advancements in attapulgite–rubber composites for engineering applications (Chapter 2) and wraps up with rectorite composites for enhanced permeability (Chapter 3). The book provides one with the most up to date information on a field that is advancing at a blazing pace, with promising new materials constantly being discovered that will certainly make their way into significant applications. I dare to predict that in five to ten years we shall discover even more fascinating properties and technological applications of nanoclay materials, especially in the area of biology which we just begin to uncover.

Nicholas A. Kotov

University of Michiganhttp://www.umkotov.com/profkotov/