Si-containing polymers

The hydrosi(ly)lations of alkenes and alkynes are very important catalytic processes for the synthesis of alkyl- and alkenyl-silanes, respectively, which can be further transformed into aldehydes, ketones or alcohols by estabhshed stoichiometric organic transformations, or used as nucleophiles in cross-coupling reactions. Hydrosilylation is also used for the derivatisation of Si containing polymers. The drawbacks of the most widespread hydrosilylation catalysts [the Speier s system, H PtCl/PrOH, and Karstedt s complex [Pt2(divinyl-disiloxane)3] include the formation of side-products, in addition to the desired anh-Markovnikov Si-H addition product. In the hydrosilylation of alkynes, formation of di-silanes (by competing further reaction of the product alkenyl-silane) and of geometrical isomers (a-isomer from the Markovnikov addition and Z-p and -P from the anh-Markovnikov addition. Scheme 2.6) are also possible. 

Relationship between thermosetting structure and characteristics of a silyl-carborane hybrid Si-containing polymer network... 

Table 5.3. The dispersion component Fd of the "molar attraction constant" calculated by group contributions, correction index Npd used in the correlation, and fitted or predicted (fit/pre) values of Fd, for 138 polymers. For 31 of the polymers, Fd was not calculated by group contributions because of missing values, but was calculated by the new correlation. Most of the connectivity indices used in these calculations are listed in Table 2.2. Alternative °XV and 1%v values used for Si-containing polymers are listed in Table 2.3. Fd is in units of jO cm /mole. 

The organo-element general group (2) in the present collection was divided into Si-containing polymers (2.1) and B-containing polymers (2.2). 

To a methyl ethyl ketone solution of =Si—containing polymers or copolymers, a cold solution (ca. -10 °C) of dimethyldioxirane in acetone was quickly added and reacted for 30 min at 0 °C. The mole ratio of dioxirane to polymer was ca. 1.2-1.3. The resulting silanol polymers or copolymers were obtained either in solution or precipitated into hexanes followed by vacuum dry at 40 C for 24 h. 

The goal of this study was to examine the effects of varying the pendant group on a common carbosilane backbone of Si-containing polymers that are obtained by ADMET in the presence of electrochemically reduced tungsten-based active species (WCl -e -AI-CH2CI2). 

Si-containing polymer membranes are desilylated to yield the membranes of poly( l-aryl-2-phenylacetylene)s. Both the starting and the desilylated polymers show very high thermal stability and high gas permeability. For instance, the To and P02 t ues of poly(l-p-naphthyl-2-phenylacetylene) are 470 °C and 4300 barters, respertively (No. 2 in Table 10). 

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