Functional polysiloxanes, synthesis

Aldehyde-Functional Polysiloxane Synthesis. Poly (dimethylsiloxanes) containing 1-hexenyl-dimethylsiloxane end groups, DC 7691 (n = 200), DC 7692 (n = 100) and DC 7697 (n = 30), were dissolved in hexane or methylene chloride (1 g/ml) and the solutions were cooled to -20°C. Ozone was then bubbled through the solutions and then into a Nal solution to decompose any excess that had not been reacted and prevent its release to the atmosphere. Treatment of the reaction mixtures with ozone was stopped after the Nal solution developed a blue color indicating that all the unsaturation had been consumed. The reaction mixtures were then allowed to warm to room temperature and heated for one hour at 40 C with Zn powder/acetic acid (1 1 molar ratio) to convert the ozonized groups on the polymers to aldehyde groups. 

The compounds I and II represent intermediates for the synthesis of either carboxy functional or amino functional polysiloxanes. To this end I or II is either saponified with sodium hydroxide and concomitantly polycon-densated to a poly(carboxylaIky1 methyl siloxane) (III) or reduced to an amino alkyl methyl dialkoxy silane with sodium borohydride (J 5). ... 

Zhou, Y. et al., Efficient catalysis of polysiloxane synthesis by silicatein a requires specific hydroxy and imidazole functionalities, Angew. Chem. Int. Ed., 38, 780, 1999. 

To date, three methods have been described for the synthesis of aldehyde functional polysiloxanes (1) in patent literature, but these are not practiced. The hydroformylation of olefinic siloxanes with carbon monoxide and hydrogen under high pressure and temperature conditions is possible (Scheme 1, eq. (1)), but produces a mixture of... 

Scheme 1 Methods for the synthesis of aldehyde functional polysiloxanes described in the literature [1-5] (1) hydroformylation, (2) and (3) ozonolysis, (4) hydrosilylation of acrolein acetals and acid hydrolysis...

Michalska ZM, Rogalski L, Rozga-Wijas K, Chojnowski J, Fortuniak W, Scibiorek M (2004) Synthesis and catalytic activity of the transition metal complex catalysts supported on the branched functionalized polysiloxanes grafted on sUica J Mol Catal A Chem, 208 187-194... 

Concerning the first method, the availability of primary amine functionalized polysiloxanes (e.g. poly(aminopropyhnethyl-co-dimethyl)siloxane) is limited. Whereas the second method allows the synthesis of polysiloxanes with varying amounts of grafts and a wide range of molecular weights via synthesized statistical poly(dimethyl-co-hydromethyl)siloxane. 

C. Racles, T. Hamaide, Macromol. Chem. Phys., 2005, 206, 1757-1768. Synthesis and characterization of water soluble saccharide functionalized polysiloxanes and their use as polymer surfactants for the stabilization of polycaprolactone nanoparticles. ... 

The anionic ROP of cyclotrisiloxane in THF initiated with lithium trialkylsilanolate or butyl lithium is our system of choice for the controlled synthesis of functionalized polysiloxanes. The polymerization proceeds in a selective way. The undesired reactions of back biting, chain transfer and terminal unit exchange may be eliminated. The initiation is fast and complete, and the quenching of polymerization by triorganochlorosilanes is fast and clean. The polymerization may be performed at low temperatures, which increases its selectivity [4, 5]. In addition, the SiOLi/THF system tolerates many functional groups in the monomer. 

Synthesis of Star-Branched and Dendritic-Branched Functionalized Polysiloxanes... 

Anionic polymerization of functionalized cyclotrisiloxanes is a good method for the synthesis of well-defined functionalized polysiloxane with control of molecular mass, polydispersion, and density and arrangement of functional groups. These polymers may serve as reactive blocks for the building of macromolecular architectures, such as all-siloxane and organic-siloxane block and graft copolymers, star-, comb- and dendritic-branched copolymers and various polysiloxane-inorganic solid hybrids. 

Section 1 considers the methods of synthesis and physico-chemical properties of new types of inorganic sorbents (complex carbon-mineral sorbents, co-precipitated hydroxides, functional polysiloxane sorbents, porous glasses with controlled porosity, colloidal silicas, aluminium oxyhydroxide colloids, apatites). These sorbents are widely used in scientific investigations, in chemical practice and are important from a technological point of view. The presented results provide additional possibilities for the preparation of inorganic sorbents possessing unique adsorption and catalytic properties. Moreover, Section 1 presents the possibilities of the computational studies on the design of synthetic materials for selective adsorption of different substances. 

Just as the hydrosilylation reaction is important in the synthesis of silanes, so it also serves as a useful route to functional polysiloxanes. The same variety of chemistry as previously described for silanes is available and two further examples are given in equations 82 and 83. One of the main advantages of this route is that the silicon hydride prepolymers are well characterized and readily available materials, which in turn leads to well-defined organofunctional products. A disadvantage is the low efficiency in the use of the precious metal catalyst and the difficulty of its recovery. This is particularly true for systems containing a low level of functionality but this can be partially overcome by using recyclable platinum catalysts on solid supports216,217. 

Scheme 6. Synthesis of dendritic-branched, functional polysiloxane.

Racles C, Hamaide T (2005). Synthesis and Characterization of Water Soluble Saccharide Functionalized Polysiloxanes and Their Use as Polymer Surfactants for the Stabilization of Polycaprolactone Nanoparticles. Macromol. Chem. and Phys. 206 1757-1768. 

Synthesis of Functionalized Polysiloxane Xerogels 399 Synthesis of Xerogels with Amino Groups... 

Salient Features of Synthesis and Structure of Surface of Functionalized Polysiloxane Xerogels... 

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