As Associate Editor of Nanocomposites, it is my great pleasure and honor to introduce this second issue. Clearly the following articles perfectly highlight how versatile and rich the field of nanocomposites can be. It is currently accepted that a nanocomposite material can be viewed as a heterophasic system where the dispersed phase (of a different nature to the continuous phase) has at least one of its dimensions in the order of a few nanometers. The continuous phase, usually called matrix, can be metallic, ceramic or polymeric, while the dispersed phase, i.e. nanofiller, can present 1, 2 or 3 nanodimensions. However, a key-question remains: what is a nanofiller? A filler with nanodimensions, in other words, a nanomaterial?
On 18 October 2011, the European Commission adopted a specific recommendation on the definition of a nanomaterial.Citation1 According to this recommendation, a nanomaterial means a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm–100 nm. On the same website, one can read further: Hundreds of products containing nanomaterials are already in use. Examples are batteries, coatings, anti-bacterial clothing, etc. Nano-innovation will be seen in many sectors including public health, employment and occupational safety and health, information society, industry, innovation, environment, energy, transport, security and space.
It turns out that nanomaterials, e.g. nanofillers, are already in use in numerous fields of applications. For illustration, in polymer matrices the most widely investigated nanofillers can be summarized as follows:
| (i) | nanosized isotropic particles, thus with 3 nanodimensions, either metallic (such an Ag, metal nanoxides, ZnO, TiO2 ferrites); inorganic (POSS, CdS, SiO2, Ca/Mg(OH)2) or organic (carbon black, fullerenes). | ||||
| (ii) | nanotubes, nanofibers and nano-needles, actually characterised by 2 nanodimensions, either inorganic (sepiolite, halloysite), metallic like titanate nanotubes, or organic (carbon nanotubes/nanofibers, cellulose/chitin nanocrystals) | ||||
| (iii) | nanolayers and nanoplatelets displaying one single nanodimension, mostly inorganic (layered double hydroxides, layered silicates/organo-clays) and organic (graphene, cristalline starch nanoplatelets). | ||||
In his Editorial of the inaugural issue of Nanocomposites, Professor Ton Peijs, Editor-in-Chief, wrote that “nanocomposites represent a relatively new class of materials alternative to conventional composite materials… offering extraordinary property improvement.”Citation2 To reach such high performance nanocomposites, several key-parameters have to be considered and tailored. Let me mention a few: the fine distribution and dispersion of the nanofillers, low interfacial tension, high interfacial adhesion, inherent nature of the nanofiller in terms of shape factor, dimensions in the nanometer range and related specific surface, chemical composition (bulk and surface), and finally the relative content in nanofiller(s), usually max. 5 wt%.
New orientations are currently given in the search of novel families of nanocomposites, such as combining two (or more) nanofillers providing synergistic behaviour, developing new processing technologies (reactive extrusion, sol-gel and layer-by-layer techniques,…) and nanostructuring the nanocomposite materials by specifically localizing and/or orienting the nanofillers, e.g., in co-continuous polymer blends using surface-treated nanoparticles as interfacial compatibilizers.
Interestingly the peer-reviewed articles presented in this second issue of Nanocomposites follow these new strategic orientations and provide some original approaches paving the way to novel materials with significant improvements in terms of crystallization behaviour (see paper by M. Murariu et al.Citation3), nanofiller dispersion ability (see papers by I. Hassinger and M. GurkaCitation4, and by Y. Kobayashi et al.Citation5), thermo-mechanical (paper by Ch. Sellam et alCitation6), gas barrier (see paper by J.F. Feller et al.Citation7), antibacterial and UV-blocking properties (see paper by V. Dhapte et al.Citation8).
So simply enjoy reading this second issue…
Yours sincerely,
Philippe Dubois
Associate Editor
References
- http://ec.europa.eu/environment/chemicals/nanotech/faq/definition_en.htm (consulted on March 28, 2015).
- T. Peijs: Nanocomposites, 2015, 1, 1–2.
- M. Murariu, A-L. Dechief, R. Ramy-Ratiarison, Y. Paint, J-M. Raquez, and P. Dubois: Nanocomposites, 2015, 2, 71–82.
- I. Hassinger and M. Gurka: Nanocomposites, 2015, 2, 63–70..
- Y. Kobayashi, R. Nagasu, T. Nakagawa, Y. Kubota, K. Gonda, and N. Ohuchi: Nanocomposites, 2015, 2, 83–88..
- C. Sellam, Z. Zhai, H. Zahabi, O. T. Picot, H. Deng, Q. Fu, E. Bilotti, and T. Peijs: Nanocomposites, 2015, 2, 89–95..
- J. F. Feller, K. K. Sadasivuni, M. Castro, H. Bellegou, I. Pillin, S. Thomas, and Y. Grohens: Nanocomposites, 2015, 2, 96–105..
- V. Dhapte, N. Gaikwad, P. V. More, S. Banerjee, V. V. Dhapte, S. Kadam and P.K. Khanna: Nanocomposites, 2015, 2, 106–112..