Organofunctional siloxanes

Performance of coupling agents in reinforced composites may depend as much on physical properties resulting from the method of appHcation as on the chemistry of the organofunctional silane. Physical solubiUty or compatibiUty of a siloxanol layer is determined by the nature and degree of siloxane condensation on a mineral surface. 

White, J.W. and Treadgold, R.C., Organofunctional Siloxanes. In Clarson, S.J. and Semiyen, J.A., Siloxane Polymers, Polymer Science and Technology Series. PTR Prentice Hall, Englewood Cliffs, NJ, 1993, pp. 193-215. 

Table 4. Important a,oj-organofunctionally terminated di-siloxanes precursors for reactive, Telechelic polyorgano-siloxanes...

General route for the Preparation of a,oo-Organofunctionally-Tenninated Siloxane Oligomers by Equilibration (Redistribution) Reactions8... 

Detailed procedures for the synthesis ofa,o>-organofunctionally terminated siloxane oligomers with well defined structures have been given 50,66-67). Tables 6 and 7 provide the data on the synthesis and characteristics of aminopropyl and hydroxybutyl terminated polydimethylsiloxane oligomers prepared via anionic and cationic ringopening polymerization of octamethylcyclotetrasiloxane (D in the presence of appropriate disiloxanes, respectively. 

Optimization of geometry 180-182 Organofunctional siloxane oligomers see Macromonomers... 

Organofunctional siloxane oligomers, amino-propyl-terminated 15, 25, 26, 37, 38... 

Silane coupling agents have the structure R—Si—X3, where R represents an organofunctional group and X is generally alkoxy. They are generally applied from water solutions or from organic solvent-water mixtures. In the presence of water, hydrolysis occurs step-wise to form alkoxysilanols, and eventually silane triols. Condensation of the silanols to siloxanes also occurs. Reactions shown schematically below ... 

As in previous years the major method used for attaching an organofunctional group to a siloxane backbone is hydrosilylation. Even in this much studied field there is still the potential for surprising and potentially very useful results. Thus, Crivello and Bi... 

Some researchers continue to investigate alternatives to hydrosilylation or Grignard chemistry for the preparation of organofunctional siloxanes. One such example is the... 

Surface coating using sol-gel technology is mainly used for the preparation of oxide or organofunctional siloxane layers on solid materials. In this case, the material is dipped or spun in the TEOS sol. This procedure leads to the formation of multilayered coatings of irreproducible thickness. Since this type of coating may only be used for axially or radially symmetric materials, alternatives have been developed. Those include spraying, electrophoresis, thermophoresis and ultrasonic pulverization.63 However, these are not of interest in powder modification. 

Snow, S.A., Fenton, W.N. and Owen, M.J. (1991) Zwitterionic organofunctional siloxanes as aqueous surfactants - synthesis and characterization of betaine functional siloxanes and their comparison to sulfobetaine functional siloxanes. Langmuir, 7(5), 868-71. 

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