2Per materiali nanostrutturati s’intendono materiali costituiti da particelle con dimensioni < 100 nm.To call them “nanomaterials” at least one of their dimensions must be in the rangebetween nm (nanometres). This means, clusters of atoms or grains less than100 nm in size, fibres less than 100nm in diameters and films with thickness less than100 nm I materiali nanostrutturati sono importanti perché le loro proprietà sono molto diverse sia da quelle dei materiali “bulk” sia da quelle degli atomi isolati
3[1) “size effects”: al diminuire della dimensione delle particelle, le bande elettroniche diventano OM con valori discreti di energia proprietà ottiche e proprietà elettriche.]2) effetti di superficie: un’elevata percentuale degli atomi si trova sulla superficie i materiali nanostrutturati consentono di avere un intimo contatto e una connessione ottimale tra le particelle; hanno elevato area superficiale, che favorisce un’ adeguato scambio con l’ambiente (es. la lignina come tale) ad es. posso funzionalizzare la lignina; the use of a nanostructured component favors dispersion si può usare come nanofiller, allowing a significant improvement of the dispersion with respect to microsized or bulk materials, particularly important for loadings above 1 wt %.
5Nanoporous materialsNanoporous materials are natural or synthetic, organic or inorganic, hybrid materials,with holes less than 100 nm in diameter (are called mesopores those with a diameter of2 to 50 nm and macropores those with a 50 to 100 nm diameter)Vantaggi dei materiali nanoporosi· Increased specific surface area (together with control over pores’ size anddistribution this feature enhances adsorption properties and the possibilities forsurface chemistry);· Improved sieving (including selectivity);· Reduced weight;· Thermal insulation;· Photonic properties (nanoporous materials can be tailored to exhibit photoniccrystals properties).
6SINTESI DEI MATERIALI NANOPOROSI · Solution precipitation routes (incl. sol-gel);· Self-assembling;· Liquid crystal routesThe solution precipitation routes could be used to produce a wide range of materialstructures such as nanoporous membranes and aerogels. The fact that the processworks at room temperature enables its use in bio-encapsulation related applications.Self-assembling is a bottom up approach and its main advantage is that it doesn’trequire scaling down the manufacturing tools (as in all top down productions), uses lessraw material and produces less wastes. Finally, liquid crystal phases (at high enoughconcentrations) can replicate their liquid crystalline structures
7Nanoparticles/Nanocomposites Nanoparticles are usually referred to as particles with a size up to 100 nm. Below thissize the physical properties of the material do not just scale down or up, but change tocompletely new or greatly improved properties. Even though nanoparticles can be madeof a wide range of materials, the most common are metal oxide ceramics, metals,silicates and non-oxide ceramics.VANTAGGI DELLE NANOPARTICELLEHigh specific surface area (very high surface to volume ratio);· Magnetic and Electric properties (improved/specific magnetic and electricproperties);· Optical properties: (absorption or emission wavelengths can be controlled by sizeselection, interaction with ligands and external perturbation.);· Chemical properties (enhanced chemical reactivity).
8SINTESI DELLE NANOPARTICELLE Solid state methods (grinding, milling, mechanical alloying techniques);· Vapour methods (Physical Vapour Deposition – PVD, Chemical VapourDeposition – CVD ;· Chemical synthesis /solution methods (sol gel, colloidal chemistry);· Gas-phase methods (flame pyrolysis, electro-explosion, laser ablation, plasmasynthesis).
9DENDRIMERIA dendrimer is generally described as a macromolecule which is characterized by itshighly branched 3D structure that provides a high degree of surface functionality andversatility. Its structure is always built around a central multi-functional core molecule,with branches and end-groups. Dendrimers can be made out of virtually anything thatcan branch (metal atoms, organometallic groups, or purely organic materials) and canhave a variety of functionalities depending on what they are built of and how.VANTAGGI DEI DENDRIMERIpolyvalency (easy surface functionalisation with different ligands);defined architecture, size and shape control;· monodispersity (consistency of shape and form between molecules);· loading capacity,· biocompatibility / low toxicity (some);· transfection properties (transporting genetic material into cell interiors).
10SINTESI DEI DENDRIMERI There are different methods to synthesise dendrimers. However two, the so calleddivergent and convergent synthesis, are the most common and extended ones. Ingeneral, it could be said that the convergent approach is appropriate for obtaining smalldendrimers while the divergent approach is good for obtaining the large ones. For boththe main technical challenges are found in establishing process control methods, highpurity and well defined products, specifications and final product analytical methods.
11SINTESI DEI FILM SOTTILI Chemical Vapour Deposition (CVD);· Physical Vapour Deposition (PVD);· Sol gel· Electrodeposition/electroplating· Spin coating· Spray coating ;
12Thin film & coatingsThin films and coatings are material structures resulting from the deposition of one ormore layers of material onto a surface. In the case of this report, the thickness of the thinfilm considered is below 100 nm.The main advantage of thin films (or any other coating for that matter) is that theproperties of the materials deposited can be acquired by the surface. The substrate andthe thin film become a material system where each of them provides the requiredfunctionality. In general, nanotechnology provide the tools for better controlling three keyparameters of the surface deposit: chemical composition (and crystalline nanostructure), thickness and topography.
14PACKAGING TECHNOLOGY AND SCIENCE Packag. Technol. Sci. 2007; 20: 325–335Published online 27 October 2006 in Wiley InterScience (www.interscience.wiley.com). DOI: /pts.761Innovative Packaging for Minimally Processed FruitsBy M. Avella,1,* G. Bruno,2 M. E. Errico,1 G. Gentile,1 N. Piciocchi,2A. Sorrentino2 and M. G.Volpe2Novel nanocomposite films for use in the packaging of foods ready for consumptionand based on isotactic polypropylene (iPP) filled with innovative calciumcarbonate nanoparticles, as well as having spherical and elongated shape andcovered with appropriate coating agent able to better interact with the iPP matrix,were prepared and characterized. Morphological, thermal, mechanical andtransport characterizations on nanocomposite films were performed. The resultsevidenced a good dispersion of the nanofiller into the polymeric matrix as well asan increase in mechanical parameters such as modulus. Moreover, a drasticreduction of iPP permeability to both oxygen and carbon dioxide was alsorecorded.
15Morphological and Optical Characterization of Polyelectrolyte Multilayers Incorporating Nanocrystalline CelluloseEmily D. Cranston and Derek G. Gray*Received March 24, 2006; Revised Manuscript Received July 3, 2006Aqueous layer-by-layer (LbL) processing was used to create polyelectrolyte multilayer (PEM) nanocompositescontaining cellulose nanocrystals and poly(allylamine hydrochloride). Solution-dipping and spin-coating assemblymethods gave smooth, stable, thin films. Morphology was studied by atomic force microscopy (AFM) and scanningelectron microscopy (SEM), and film growth was characterized by X-ray photoelectron spectroscopy (XPS),ellipsometry, and optical reflectometry. Relatively few deposition cycles were needed to give full surface coverage,with film thicknesses ranging from 10 to 500 nm. Films prepared by spin-coating were substantially thicker thansolution-dipped films and displayed radial orientation of the rod-shaped cellulose nanocrystals. The relationshipbetween film color and thickness is discussed according to the principles of thin film interference and indicatesthat the iridescent properties of the films can be easily tailored in this system
16Dendritic cyclotriphosphazene derivative with hexakis(alkylazobenzene) substitution as photosensitive trigger Takafuji, Makoto; Shirosaki, Tomohiro; Yamada, Taisuke; Sakurai, Toshihiko; Alekperov, Dzhamil; Popova, Galina; Sagawa, Takashi; Ihara, Hirotaka.A dendritic cyclotriphosphazene deriv. [i.e., 2,2,4,4,6,6-hexakis[4-[[4-(dodecyloxy)phenyl]azo]phenoxy]-2,2,4,4,6,6-hexahydro-1,3,5,2,4,6-triazatriphosphorine] (I) was prepd. by substitution with six alkylazobenzenes onto cyclotriphosphazene. Photoinduced trans-to-cis isomerization of the azobenzene moieties in I was discussed on each substituent. It was also investigated whether the dendrimer acted as a photosensitive trigger for microenvironmental modification of chirally self-assembled organogels through the isomerization. Organogels of I with a lipophilic L-glutamide deriv. were prepd. and investigated. Photosensitive azobenzene derivs. have potential applications for control of drug release, orientation of liq. crystal mols., elec. cond. of films, and to induce self-organization of dye mols. The properties of 2-[4-[[4-(dodecyloxy)phenyl]azo]phenoxy]-2,2,4,4,6,6-hexahydro-1,3,5,2,4,6-triazatriphosphorine (II) in an organogel with a lipophilic L-glutamide deriv. and effects of UV irradn. in CD spectra were also studied.
17Nanocrystalline Cellulose and Poly(allyl)amine Hydrochloride Multilayers for Ordered Thin Films Cranston, Emily D.; Gray, Derek G.; Barrett, Christopher J. Department of Chemistry, McGill University, Montreal, QC, Can.Anisotropic nanocryst. cellulose was prepd. by acid hydrolysis of cellulose fibers resulting in a stable colloidal suspension of rod-shaped crystals ( nm long by 5-10 nm wide). Electrostatic layer-by-layer self-assembled films of the nanocryst. cellulose and poly(allyl)amine hydrochloride (PAH) were prepd. by spin-coating and conventional dip-coating. Surface characterization was performed with at. force microscopy, indicating that the nanocrystals were evenly dispersed and that complete coverage was achieved after 5-10 layers. Surface orientation of the nanocrystals, film roughness and stability to solvent were compared for the two multilayer prepn. methods. Similar results were obtained for surface orientation and root-mean-square roughness in spin-coated and dipped films. Ionically crosslinked dip-coated films were stable in water whereas physisorbed spin-coated films re-dispersed in solvent. Attempts were made to induce alignment of the cellulose nanocrystals by varying the substrate, substrate pre-treatment, cellulose concn. and by applying a magnetic field. Two-dimensional order parameters were calcd. to quantify orientation in multilayered thin films of nanocryst. cellulose and PAH.