Polyhedral oligomeric silsesquioxanes structures

The polyhedral oligomeric silsesquioxane structure affects the rheological and cure characteristics but was found to have no discernible influence on the properties in the cured state. 

Brus J, Urbanova M, Strachota A (2008) Epoxy networks reinforced with polyhedral oligomeric silsesquioxanes structure and segmental dynamics as studied by solid-state NMR. Macromolecules (Washington) 41(2) 372-386. doi 10.1021/ma702140g... 

Controlled hydrolysis of RSiX3 compounds gives so-called silsesquioxanes or POSS compounds (Polyhedral Oligomeric SilSesquioxane), which can be used as models for silica surfaces or supports for catalysts [4] (Figure 18.2, schematic structure on the right). 

FIGU RE 8.2 General structure of polyhedral oligomeric silsesquioxane. (From http //www.hybridplastics.com.)... 

Polyhedral oligomeric silsesquioxanes (POSS) are known molecules having various structures [1] as seen in Fig. 1. However double-decker shaped silsesquioxane has not been obtained. POSS is an interesting class of monomers for the preparation of silicon-based polymers. In recent years, silsesquioxane-based polymers have received much attention because of their useful properties, which include heat resistance, mechanical stability, low dielectric constant, etc. [2, 3],... 

It has been known for some time that SiO cage compounds, polyhedral oligomeric silsesquioxanes (POSS), are important three-dimensional materials for both lubricants and coatings (56). Very recently, there has been increasing interest in the titanium analogs of the POSS, both fully and partially substituted POSS. Important issues include the structure of the Ti cage compounds, their... 

Polysilsesquioxanes are a class of compounds having the emperical formula [RSi(0)3/2] , in which three oxygen atoms and one alkyl or aryl group are attached to the silicon atom. These compounds are formed under various reaction conditions and can take various three-dimensional structures. They can be random, ladder, or even cage. Polyhedral oligomeric silsesquioxane (POSS) is usually abbreviated as T , in which n indicates the number of silicon atoms in the frame structure. 

A new chain-extender additive [185, 190] based on the cage-structured silanol derivative epoxycylohexyl polyhedral oligomeric silsesquioxane has been suggested to be a useful additive. 

All of the chapters of the first edition were updated and 11 entirely new chapters added. Four of them focus on novel polymeric structures, specifically dendrimers, polyrotaxanes, foldamers, and supramolecular polymers in general. Another group of chapters covers reinforcing phases in polymers, including carbon black, silica, clays, polyhedral oligomeric silsesquioxanes (POSS), carbon nanotubes, and relevant theories. The final new chapter describes experiments on single polymer chains. 

Zhang, Y., Lee, S., Yoonessi, M., Liang, K., Pittman, C.U. Phenolic resin-trisilanolphenyl polyhedral oligomeric silsesquioxane (POSS) hybrid nanocomposites structure and properties. Polymer 47, 2984-2996 (2006)... 

Pan, G. Mark, J. E. Schaefer, D. W., Synthesis and Characterization of Fillers of Controlled Structure Based on Polyhedral Oligomeric Silsesquioxane Cages, and Their Use in Reinforcing Siloxane Elastomers. J. Polym. Sei., Polym. Phys. Ed. 2003,41,3314-3323. 

Liu, L. Tian, M. Liang, G. Chen, W. Zhang, L. Mark, J. E., Polyhedral Oligomeric Silsesquioxane (POSS) in a Polysiloxane Melt and Elastomer. Dependence of the Dispersion of the POSS on Its Solubility and Constraining Effects of a Network Structure. J. Macromol. Sci., PureAppl. Chem. 2007,44,... 

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. 

One final class of materials that is being increasingly considered for use in composites is that based on polyhedral oligomeric silsesquioxanes (BOSS) (see Hybrid plastics) (8,14,32-34). A variety of different cage structures have been discovered, but more recently the cubic structure is receiving increased attention... 

Ahmed M, Ghanbari H, Cousins BG, Hamilton G, Seifafian AM. Small cahbre polyhedral oligomeric silsesquioxane nanocomposite cardiovascular grafts influence of porosity on the structure, haemocompatibility and mechanical properties. Acta Biomater 2011 7 3857-67. 

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