compared to the sectors listed in table 1.1, nanomaterials manufacturing is relatively young. Most attention has been focussed on the discovery and design of nanomaterials. Although the use of nanomaterials can be back-dated to the 9th century (see chapter 2, section 2.2), the large-scale commercial production of engineered nanomaterial developed and accelerated around the late 1990s and early 2000s [9]. This means that the manufacturing-related developments for nanomaterials are in their infancy, and for a vast majority of newly discovered nanomaterials, large-scale manufacturing does not exist. In other words, we are happy to have some process for the large-scale manufacturing of desired nanomaterials, while little or no attention is given to the sustainability of the process. However, this needs to change and the time is ripe to focus on the environmental impact of nanomaterials production, in order to apply the developments enjoyed by other sectors, listed in table 1.1, to nanomaterials production. These factors clearly stress the urgent need for developing fundamentally new production methods for nanomaterials that are green and sustainable. This change in thinking is very important, and previous experience suggests that when sustainability/green principles are included at the discovery stage, this provides the most benefits.
This book focuses on stimulating a shift towards a sustainable approach for nanomaterials—from discovery to production. Chapter 2 will serve as an introduction to nanomaterials. Their properties will be discussed and benefits offered from their use in selected applications will be presented. In chapter 3, we will provide an overview of the analytical techniques used to probe various properties of nanomaterials. Chapter 4 will present, with examples, a range of current manufacturing processes used to produce nanomaterials at large scales. We will discuss these processes for sustainability by using the theory and concept of green chemistry covered in chapter 1. Chapter 5 will summarise the benefits of using nanomaterials, while highlighting the need for greener alternatives. In chapter 6, we will detail how biology produces a range of inorganic materials from macro to nanomaterials and point out the potential for learning from biology. This learning will be consolidated in chapter 7 where strategies for developing biologically inspired green routes to produce nanomaterials will be presented. The key advantages and opportunities from these alternative routes will be identified, and further explained in chapters 8 and 9 with two case studies.
References
[1] Lancaster M 2010 Green Chemistry: An Introductory Text 2nd edn (Cambridge: Royal Society of Chemistry)
[2] Gro Harlem Brundtland 1987 Development and international co-operation: environment, the United Nations, A/42/427 1987, http://www.un-documents.net/wced-ocf.htm
[3] Basics of Green Chemistry [cited 2016 23rd March]; Available from: https://www.epa.gov/greenchemistry/basics-green-chemistry
[4] Anastas P T and Warner J C 1998 Green Chemistry: Theory and Practice (Oxford: Oxford University Press)
[5] Sheldon R A 1997 J. Chem. Technol. Biotechnol. 68 381
[6] Sheldon R A 2007 Green Chem. 9 1273
[7] Windsor R, Cinelli M and Coles S R 2018 Curr. Opin. Green Sustain. Chem. 12 69
[8] Drummond C, McCann R and Patwardhan S V 2014 Chem. Eng. J. 244 483 Lieberman M B 1989 Strat. Manage. J. 10 431
[9] Vance M E, Kuiken T, Vejerano E P, McGinnis S P, Hochella M F, Rejeski D and Hull M S 2015 Beilstein J. Nanotechnol. 6 1769
Section II
Nanomaterials
Image courtesy of Lightspring/Shutterstock.
We have learnt the benefits of green synthesis, but before we can explore sustainable bioinspired green synthesis of nanomaterials, it is important to understand what nanomaterials are, and how we can use them. Nanomaterials, nanotechnology and particularly biomedical applications of nanotechnology have captured our imagination in both science and fiction for decades, even before nanotechnology was scientifically realised: the concept of nanobots, removing diseased cells from our blood stream, is a very clear image in sci-fi literature, and excitingly it is actually something that we believe will become a reality in the coming years.
This section is devoted to highlighting special properties of nanomaterials within the scope of this book, illustrating their functions and how these properties serve several emerging and well-known applications with selected examples. Given these special features, which may not be found in bulk materials, an entire chapter focuses on giving an introduction to various key characterisation techniques used for studying and measuring properties of nanomaterials. This is followed by a description of ‘top-down’ and ‘bottom-up’ current and emerging methods for nanomaterials synthesis and manufacturing along with the physicochemical principles of nanomaterial formation. Suitable examples of the chemistry of materials are provided to help illustrate the processes.
IOP Publishing
Green Nanomaterials
From bioinspired synthesis to sustainable manufacturing of inorganic nanomaterials
Siddharth V Patwardhan and Sarah S Staniland
Chapter 2
Nanomaterials: what are they and why do we want them?
2.1 Fundamentals of the nanoscale
Although the term ‘nanotechnology’ is commonly used beyond science by the general public and in the media, an understanding of what ‘nano’ is defined in length scale, and the changes to physical properties that occur in materials in this miniaturised world, are not generally realised.
‘Nano’ comes from the Greek word for ‘dwarf’ and is the prefix of a measurement that is ×10−9 (or one billionth of that unit). In the context of material science and nanomaterials we are interested in the measurement unit of length: metres, and therefore the nanometre (nm), although ‘nano’ can prefix any unit, for example nanosecond, nanogram or nanomole. Put into context, there are one million nanometres in a millimetre and a billion in a metre. Figure 2.1 may be used to aid visualisation of these different length scales. Considering it from the opposite side, scaling up rather than down, we measure atomic bond lengths in Angstroms (Å) which are ×10−10 m, and so the nanometre length scale is 10× larger than the length scale at which we consider atomic reaction (chemistry) to occur. For example, the unit cell (smallest crystal unit) of sodium chloride is 0.56 nm2, containing four of each type of (sodium and chloride) atoms. Although performing
