Nanosponges: Synthesis and Applications

In the last few decades, the prefix “nano” was included in a great deal of words not only in the scientific language but also as part of everyday life vocabulary. Although the word “nanotechnology” was first introduced for the first time by Norio Toniguchi in 1974 during a talk at an international conference, the roots of this science is often linked to the Richard Feynman’s lecture at Caltech in 1959. The famous sentence “there is a plenty of room at the bottom” can be considered the first milestone of nanotechnology and a visionary horizon. To date, the word nano has been included 86,635 times in the title of scientific articles, according to Scopus, or 342,190 times if abstract (194,056) and keywords (194,281) are included too. This simple numbers give the taste of the tremendous importance of nanomaterials and nanotechnology. Nanoscience and nanotechnology have shown – and still continuously show – an incredible growth of application leading to impressive advancement of fundamental knowledge and performances in medicine, electronics, mechanics, optics, computer science, drug delivery, paint, sensors, photonics, robotics, artificial intelligence, cosmetics, textiles, food packaging, just to mentions the main fields. Actually, there is no field of modern technology without the presence of nanomaterials. The growing of the number of applications of nanomaterials is impressive: It is estimated that about 3-4 new products reach the market every week and the list of such materials are now quite astonishing. In the recent years, several Nobel laureates in chemistry or physics took the prize for the studies in the nanoworld. As explained in the first chapter of this book, nano-world spans the range between 1 and 100 nm i.e below the submicron range (100-1000 nm) but above the quantum range (less than 1 nm), now referred to as the pico range. A relevant limit on the applications and used of nanomaterials derived from health concerns. This seems to be particularly true for nanofiber and, although to a lesser extent, for nanoparticles. On this basis, it is also understandable how nanocarriers for drug delivery still have limited applications. Nanosponges do form a different class of nano object. In fact, from a morphological point of view they can assume dimensions in the micro range or even larger. Nevertheless, they generally present a nanoporous structure providing these materials with unique properties and ruling out the health concern related to the nanometric dimensions of the particles. From this standpoint, nanospanges can be considered relatively safe material. Although the papers directly linked to the term nanosponges are not so numerous, nevertheless the world of porous, nano-structurated materials or highly cross-linked materials is quite large. In many cases the synthetic processes leading to nanosponges are simple, especially if compared to classical nanomaterials. Nanosponges show tunable properties, high versatility, low cost synthetic routes, high stability and excellent absorption properties, making them ideal materials for the removal of unwanted molecules from the environment or, on the other hand, for the selective release of added value compounds, as in drug delivery or in targeted and controlled release. The aim of this book is to provide the reader with state-of-the-art reviews of the fundamental and applicative aspects of nanosponges, thus filling the gap between nanomaterials and this new class of nanoporous, functional materials, underlining both basic and advanced information for those researchers willing to approach these fascinating, novel and high performance materials. Francesco Trotta Andrea Mel