Silicones synthesis

Direct particle interception, in depth filtration theory, 11 339 Direct potentiometry, 9 582—585 Direct printing, 9 218 Direct process, silicone synthesis via,... 

The most important monomers (> 95 % by weight) for silicone synthesis are the methyl chlorosilanes. Next to them are the phenyl chlorosilanes, methyl phenyl chlor-osilanes, methyltrifluoropropyl chlorosilanes, and a variety of silanes containing organic functional groups such as hydroxyl, amine, epoxy, acrylate and carboxyl which are responsible for the different products. 

The synthesis of oligomeric peralkylated polyaminophosphazenes based upon the P3 and P4 templates is an elegant (but complicated), hazardous, and expensive multi-step process. To exploit catalysts of this type in silicone synthesis on an industrial scale would require a much simplified and lower-cost synthetic protocol. One of the simplest and lowest-cost routes to a conjugated -P=N- template that forms the framework for the synthesis of phosphazene base materials is via phosphonitrilic chloride oligomers (Fig. 3). These are well-known acidic catalysts used in the silicone industry for the condensation polymerization of silanol-terminated polydimethylsiloxanes. Catalysts of this type are most commonly prepared by the reaction of PCI5 with NH4CI or HMDZ,... 

Almost all fimctional silicone fluids of today s industrial production are either of a cyclic nature, containing the appropriate residues, or are linear oils bearing reactive functionalities at both ends or in the chain. The chemical nature of silicone synthesis done by equilibration and condensation is prohibitive for formation of asymmetrical silicones, in contrast to organic molecules like oleic acid or even ethanol. Currently there is only one way of preparing monofunctional silicone fluids, which is through kinetic anionic ring opening polymerization of the cyclic silicone monomer hexamethyl-cyclotrisiloxane (D3). 

Silane- and siloxanediols are important intermediates in silicone synthesis. During the technical chloro- or alkoxysilane hydrolysis the primary-formed silanols and siloxanols react preferably in the aqueous phase due to their considerable water solubility. To get more information on these reactions in water we investigated some silane- and siloxanediols using a method already described [1]. 

Carlisle EM and Alpenfels WF (1984) The role of silicon synthesis. Fed Proc 43 680. 

Short-Lived Intermediates with Double Bonds to Silicon Synthesis by Flash Vacuum Thermolysis, and Spectroscopic Characterization... 

Nature Meets Silicones — Synthesis and Properties of Modern Organomodified Silicones... 

Keywords B(C6Fs)3 Controlled 3D silicone structures Dehydrocarbonative condensation Piers-Rubinsztajn reaction Silicone synthesis... 

One consequence of the reactivity of silicones towards acidic or basic conditions is that it is exceptionally difficult to reliably assemble complex silicone structures. Almost inevitably, the reaction conditions used to create a structure also lead to structural fragmentation. Even linear polymers of narrow molecular weight are difficult to prepare on a large scale and in good yield. The very few reports of controlled silicone synthesis, for example, of a silicone dendrimer [3], utilize difficult-to-reproduce and non-generic reaction conditions. 

Rubinsztajin and co-workers reported in 2004 that Piers observations that alkoxysi-lanes and organohydrosilanes will react in the presence of B(C6Fs)3 could be more generally applied to silicone synthesis (Fig. 9) [11,12,46]. Very low levels of catalyst were required, typically less than 1 mol%. Under these conditions the condensation process proceeds to produce nearly perfectly alternating siloxane polymers (i.e., no... 

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