Hybrid precursors

Figure 18.3 Control of hybrid precursor or monomer/polymer location within self-assembled porous materials controlled by partitioning of precursors between silica and surfactant phases.

Although PMOs and related materials have many potential applications, including adsorbants,49,50 sensors,51 and catalysts,52,53 we focus here on two specific classes of functional materials, nanovalves and polymer-silica nanocomposites formed via the co-assembly of hybrid precursors (or polymer-monomer species) with surfactant mesophases. 

Finally, structural characterization of hybrid materials must be refined in many cases, it is unclear where the organic component is located within the overall meso-stmcture of the material. Coupled with experimental data, simulations of the self-assembly process in hybrid materials79 should yield greater insight into the local structure of hybrid precursors. 

Synthesis of Hybrid Precursor fi-CDAPS Containing Amino Groups and fi-CD Moieties... 

The soft experimental conditions in the synthesis of P-CDAPS were optimized using experimental design. The hybrid precursor P-CDAPS has been characterized in order to determine its structure. ETIR spectra show the presence of amino groups (1564cm ) on one hand and siloxane structure (1100-1000cm ) on the other hand, conhrmed by TGA measurements. This TGA gave a Si ratio of 5.80 0.04%., conhrmed by elemental analysis. N content was determined by elemental analysis at 2.98 0.02%, which corresponds to 2.13 0.04mmol/g of amine functions, also deduced from amine titration. 

So a model, consisted of three types of units with x, y, z as molar ratios for each one, was assumed (Fig. 1) y is fixed at 1, z at 0.1 (considering the amount of ditosyl P-CD) and x can vary. From this model, we calculated theoretical values of Si, C, N, FI contents for different values of x and compared it with experimental contents. Finally, the best accordance led to a structure of the hybrid precursor p-CDAPS, close to 2.3 aminopropyl groups (x=2,3 in Fig. 1) for 1 P-CD group. 

Narisawa M, Okabe Y, Iguchi M, Okamura K (1998) Synthesis of ultrafine SiC powders from carbon-silica hybridized precursors with carbothermic reduction. J Sol-Gel Sci Technol 12 143-152... 

The addition of a source of molybdate anions to the hybrid precursor solution gave rise to the formation of a denser siloxane network and to a substantial increase in Tg of the organic phase. This also resulted in a large increase in the rubberyplateau modulus and in a substantial reduction in both the rate of solvent uptake and the equilibrium amount of solvent absorption. These effects are illustrated in Figures 24.8 and 24.9. 

Multiscale microlens arrays can be directly fabricated on a hydrophobic flat surface by a simple inkjet printing technique (20). Inorganic/organic hybrid precursor polymers based on silicones are used. These structures are modified with organic structures that can be eventually crosslinked (21). 

H36.12J clonally derived, C57BL/6N-mouse hybrid precursor macrophages were found useful to evaluate the mechanisms by which Be stimulates macrophage cytokine production, and by which T cell derived IFN-y amplifies TNF-a production in granulomatous disease (Sawyer et d. 2000). The response was maximal at 100 jiM BeS04 and did not occur when 12j cells were stimulated with either aluminium sulphate of cobalt sulphate. Beryllium stimulated the production of 725125 pg/ml TNF-a protein by 12j cells as measured by ELISA of culture supernatants after 24 h. As measured by RT-PCR, Be-stimulated 12j cell TNF-a protein production was accompanied by an increased intracellular TNF-a mRNA at 3 and 24 h. The addition of 10 U or 1(X) U of recombinant-Mu-IFN-y to Be-stimulated 12j cells further increased TNF-a production 1.5-4... 

Figure 28.3 Molecular structures of siloxane hybrid precursors. DCM= 4-dicyanomethy-lene-2-methyl-6-[p-(dimethylamino)styryl]-4/-/-pyran PBD= 2-(4-biphenylyl)-5-(4-ferf-butyl-phenyl)-1,3,4-oxadiazole NABUP= A/-(4-butyl-phenyl)-4-[(A/-2-hydroxyethyl)(methyl)amino] naphthalimide TPPy = 1,3,6,8-tetraphenylpyr-ene PHEMA= poly(2-hydroxyethyl...

Table 28.2 Molecular structure of some organic-inorganic hybrid precursors and emission quantum yield values of the corresponding materials.

BTES-EDOT was copolymerized with EDOT by the action of iron(III)-tosy-late in the presence of prepolymerized PEDOT to a hybrid precursor, which then could be cured to conducting films on poly(ethyleneterephthalate) sheets. After rinsing residual iron salts with water, anorganic-organic hybrid conducting films with acceptable conductivity and transparency, but improved hardness and solvent resistance, could be obtained. ... 

Figure 10.4 TEM image of (a) RGO nanosheets, (b) Mn02/RGO hybrid precursor, and (c) spinel LiMn204/RG0 hybrid, [d) HR-TEM image of an individual spinel LiMn204 nanoparticles on RGO nanosheets (the inset shows the direct line scanning anatysis profile of the spinel LiMn204 nanoparticle). Reprinted with permission from Ref. 15. Copyright 2011, Royal Society ofChemistiy.

Yan, Y, Huang, Z., Dong, S., Jiang, D. (2006). New route to synthesize ultra-fine zirconium diboride powders using inorganic- organic hybrid precursors. Journal of the American Ceramic Society, S9(ll), 3585-3588. doi 10.1111/j.l551-2916.2006.01269.x. 

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