Silsesquioxane nanoparticles

Mabry, J. M. Vij, A. Viers, B. D. Grabow, W. W. Marchant, D. lacono, S. C. Ruth, P. N. Vij, I., Hydrophobic Silsesquioxane Nanoparticles and Nanocomposite Surfaces Overview of the Synthesis and Properties of Fluorinated Polyhedral Oligomeric Silsesquioxane (POSS) and Fluorinated POSS Nanocomposites. In Science and Technology of Silicones and Silicone-Modified Materials, Clarson, S. J. Fitzgerald, J. J. Owen, M. J. Smith, S. D. Van Dyke, M. E., Eds. American Chemical Society Washington, DC, 2007 Vol. 964,... 

Fig. 7 Examples of polyhedral oligomeric silsesquioxane (POSS) nanoparticles used to induce homeotropic alignment in nematic liquid crystals...

Similarly, numerous different nanoparticles, including organomodified clays,3 nanoparticles of silica,4 layered double hydroxides (LDH),5 or polyhedral silsesquioxanes (POSS),6 have been combined with intumescent formulations in polymeric materials to create large synergistic effects (see Chapter 12 for more details) the nanoparticles acting as char reinforcer or char expander that result in differences in terms of FR properties. 

The 0-d nanoparticles can be nano-metal oxides (such as silica,1 titania,2 alumina3), nano-metal carbide,4 and polyhedral oligomeric silsesquioxanes (POSS),5 to name just a few the 1-d nanofibers can be carbon nanofiber,6 and carbon nanotubes (CNT),7 which could be single-wall CNTs (SWCNT) or multiwall CNTs (MWCNT) etc. the 2-d nano-layers include, but are not limited to, layered silicates,8 layered double hydroxides (LDH),9 layered zirconium phosphate,10 and layered titanates,11 etc. 3-d nano-networks are rarely used and thus examples are not provided here. 

Rotello et al. used a similar system, relying mainly on multiple thymine/2,6-diamino-pyridine interactions (Fig. 72). Small molecules (such as flavines [241], ferrocenes [242]) can be boimd via a single, thymine/2,6-di-aminopyridine interaction. This can lead to materials with reversible properties, where the redox activity of the surface-bound functional moiety can interact with a current form of the (Au-) surface. The concept has been extended to nanoparticles (Au-NP) [243] and polyhedral ohgomeric silsesquioxanes [244]. The presence of the oligomeric silsesquioxanes was proven by XPS measurements, detecting the Si(2p) peak on the surface after deposition. 

Broadband dielectric spectroscopy is a powerful tool to investigate polymeric systems (see [38]) including polymer-based nanocomposites with different nanofillers like silica [39], polyhedral oligomeric silsesquioxane (POSS) [40-42], and layered silica systems [43-47] just to mention a few. Recently, this method was applied to study the behavior of nanocomposites based on polyethylene and Al-Mg LDH (AlMg-LDH) [48]. The properties of nanocomposites are related to the small size of the filler and its dispersion on the nanometer scale. Besides this, the interfacial area between the nanoparticles and the matrix is crucial for the properties of nanocomposites. Because of the high surface-to-volume ratio of the nanoparticles, the volume fraction of the interfacial area is high. For polyolefin systems, this interfacial area might be accessible by dielectric spectroscopy because polyolefins are nonpolar and, therefore, the polymeric matrix is dielectrically invisible [48]. 

Kaneko Y, Arake T (2012) Sol-gel preparation of highly water-dispersible silsesquioxane/ zirconium oxide hybrid nanoparticles. Int J Polym Sci 2012 1-6... 

Hessel CM, Henderson EJ, Veinot JGC (2006) Hydrogen silsesquioxane a molecular precursor for nanocrystalline Si-Si02 composites and freestanding hydride surface terminated silicon nanoparticles. Chem Mater 18 6139-6146... 

Compositematerialcontainingatleastonephasewithconstituentsofl-lOOmn in size can be termed nanocomposites. Nanoparticles commonly used in the nanocomposite include single-walled carbon nanotube (SWCNT), double-walled carbon nanotube (DWCNT), multi-walled carbon nanotubes (MWCNT), carbon nanofiber (CNF), graphite nanoplatelet (GNP), mont-morillonite (MMT), nanoclay and polyhedral oligomeric silsesquioxanes (POSS). Other nanoparticles, such as SiOj, AljOj, TiOj and nanosilica are also used in the nanocomposite. The potential benefits of the nanoparticles for structural and multifunctional nanocomposites are sunamarized below. 

---