Methylsilsesquioxane

The sol-gel methodology can also be applied to non-hydrolytic processes. The preparation of methylsilsesqui-oxane-titanium oxide hybrid by the etherolysis-condensation of a mixture of methyltrichlorosilane and metal chloride,353 354 and by the condensation of preformed poly(methylsilsesquioxane) carrying Si-OH and Si-OCHj groups with titanium(iv) -butoxide,355 has been reported. 

X-ray data are available only for the readily accessible octasilsesquioxanes and deca(methylsilsesquioxane) (Table 6). The crystal lattices of octa(alkylsilsesqui-... 

The deca(methylsilsesquioxane) molecule consists of five tetrasiloxane and two plicate pentasiloxane rings (Fig. 2). The silicon and oxygen atoms lie in two nearly parallel planes separated by approximately 0.3 A. The silicon atoms occupy the tops of the pentagonal prism and the oxygen atoms are located at the edges. 

IR spectrometric data reveal that the thermolysis of octa(methylsilsesquioxane) is a heterogeneous reaction involving the formation of a non-volatile solid phase similar to SiOj In a helium atmosphere at 150-300 °C (CHjSiO j)g almost completely evaporates without marked decomposition. When heat i in the air, however, this compound begins to decompose slowly at 270 °C, and at 450 °C an exo-effect attributed to the oxidation by air oxygen is observed When the temperature is raised to 500 °C, 66% of (CH3SiOi,5)g are oxidized to SiOj. 

If anodic bonding between glass and Si fails (due to a thick oxide layer [1 im] on Si or platinum electrode on Si), a low-melting spin-on-glass (SOG) can be applied as an adhesive. SOG, which is a methylsilsesquioxane polymer, flows very well at the temperature between 150°C and 210°C, and therefore it fills the grooves (i.e., around the Pt electrodes) for effective bonding [93]. 

Sakka, S., unpublished data.)- In the solutions, a number of methylsilsesquioxane species, formed by the hydrolysis of methyltriethoxysilane, with different structures are present even under the conditions where the cubic octamer is dominant in the aqueous silicate solutions. This indicates that the use of a silica source with tetra-functionality is required for the selective structure formation with the aid of organic quaternary ammonium ions. 

Fig. 39 Illustration of LBL fabrication of polyfvinylpyrrolidone) (PVPON) and spherical polymer brushes with a poly(methylsilsesquioxane) (PSQ) core and poly(acrylic acid) (PAA) corona. Reprinted with permission from [258], 2006 American Chemical Society...

STRUCTURE The Structure has not been reported in the literature but probably depends upon the method of preparation. Structural studies on methylsilsesquioxane are virtually nonexistent though the term ladder structure is frequently used. ... 

Poly( meth ylphen ylsiloxane) Poly(methylsilsesquioxane) Poly(methyltrifluoropropylsiloxane) Poly(phenylsilsesquioxane)... 

Superhydrophobic, stabihty, stiicone, nanofilaments, nanofibers, methylsilsesquioxane... 

Kanamori K., Aizawa M., Nakanishi K, Hanada T. New transparent methylsilsesquioxane aerogels and xerogels with improved mechanical properties, Adv. Mater. 19, 1589-1593 (2007)... 

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