POSS Polymers, Copolymers, and Nanocomposites

Methacrylate-substituted POSS macromers have been made that contain one polymerizable functional group. These macromers have been both homopolymerized and copolymerized (Fig. 8a). Propyl methacrylate-substituted POSS monomers 9 and 10, containing seven nonreactive cyclohexyl and cyclopentyl groups, respectively, are examples. SolubiUty differences between the MA-POSS monomers 9 and 10 were observed in THF, toluene, and benzene. The cyclohexyl-substituted MA-POSS 9 has approximately twice the solubility of the cyclopentyl-substituted MA-POSS 10. Furthermore, monomer 9 displayed a broad two-step thermal transition beginning at 187°C, which involves melting, thermal polymerization and decomposition, whereas 10 gave a similar thermal transition beginning at 192°C. X-ray 

Besides the enhancement of thermal stability and heat deflection temperature, the gas permeability is also affected. Oxygen permeability of cyclopentyl-substituted MA-POSS homopolymer 12/PMMA blends increased with POSS content. For example, the O2 permeability of the 10/90 weight ratio blend of MA-POSS homopolymer 12 with PMMA is about 9 times greater than that of PMMA. 

Triblock copolymers of poly(heptacyclopentyl propyl methacrylate-POSS-/)-n-butylmethacrylate-/)-heptacyclopentyl propyl methacrylate-POSS), [P((MA-POSS10)-/)-BA-/)-(MA-POSS10))], were prepared from both ends of a difunctional 

The apparent absence of LC transition temperatures and glass-transition temperatures in the hybrid copolymers with 10 mol % POSS indicated that the presence of POSS moieties in the hybrid copolymers made it more difficult to orient or order LC mesogens as the amount of the POSS component increased. Orientation became more difficult because the rigidity and bulkiness of POSS lowered the mobility and flexibility of the hybrid copolymer. Differential scanning calorimetry (DSC) and optical polarizing microscopy showed the 10% POSS copolymer had a smectic mesophase-like fine-grained texture. Moreover, the 10% POSS LC copolymer had better thermal stability than that of the corresponding LC homopolymer. 

Recently, many apphcations of MA-POSS copolymers have been developed. Random MMA/POSS copolymers were applied as compatibUizers for blending 

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Polyhedral Oligomeric Silsesquioxane (POSS) Polymers, Copolymers, and Resin Nanocomposites... 

Chapter 5 is a review of polyhedral oligomeric silsesquioxanes (POSS), hybrid POSS-organic copolymers, and POSS resin nanocomposites. Although silsesquioxanes have been known since tiie 1960s, only recently, through controlled synthesis and purification, have their structure and unique properties been determined and their useful applications been explored. This chapter is complemented by a discussion of the synthesis and properties of silica- and silsesquioxanes-containing polymer nanohybrids in Chapter 6. Chapter 7 involves a review of the preparation and characterization of siloxane-based polyviologens, polyurethanes, and divinylben-zene elastomers. 

FIG U RE 2 The novel generation cardiovascular stents coating with special nanocomposite polymers like POSS-PCU (polyhedral oligomeric silsesquioxane and copolymer caibonate-urea urethane trade named UCL-NanoTM) has been developed specifically to capture oxide nitrogen and EPC specific antibodies (factor of endothelialization) simultaneously. 

Other polymers that were used for the preparation of POSS nanocomposites are polycarbonates [72], dicyclopentadiene norbomenyl-based copolymers [73], and polypropylene [74]. 

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