Cage structures, polyhedral oligomeric silsesquioxanes

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. 

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. 

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... 

Pan G, Mark JE, Schaefer DW (2003) Synthesis and characterization of fillers of controlled structure based on polyhedral oligomeric silsesquioxane cages and their use in reinforcing siloxane elastomers. J Polym Sci B Polym Phys 41(24) 3314—3323... 

Polyhedral oligomeric silsesquioxanes (POSS) represent an important class of nanostructured materials that can be successfully used in the design of novel composite systems [1], The typical structure of POSS molecule consists of a cubic cage where the central inorganic core is functionalized with organic entities [2], The interest in POSS application for the design of polymer nanocomposites is particularly due to the fact that the organic substituents can be tailored to facilitate incorporation of the POSS molecules into the polymer martix. 

Polyhedral oligomeric silsesquioxanes have been divided into categories according to their architectural makeup. These include ladder (134) random (135), partial cage (136) and cage (137-139) structures. The cage structures 137-139 have Tg, Tjo, and Ti2 geometries, respectively. 

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