Silicone oligomers polymerizing

Fig. 46. Polymerizing silicone oligomers throughout hydrosilylation at high temperature, in the presence of a platinum catalyst.

However, full characterization of functionalized siloxanes, particularly those containing high degrees of polymerization, can be difficult. Therefore, separation techniques coupled with various detection devices are typically employed. Supercritical fluid chromatography is effective for the separation of silicone oligomers that have molecular weights less than 3000 Da (688,689). Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is applicable up to 10,000 Da (660). 

A silicon oligomer was synthesized by the polycondensation of diethoxy-dimethylsilane using lipid-coated lipase from Rhizopus delemar as catalyst in isooctane containing a small amount of water [124]. Polymerization is proposed to be initiated at the OH head group of the coating lipid. 

The weak variation of the number of moles of free silicon can be explained by the stoichiometry of the synthesized compounds (1 Si for 12 Mo atoms) [2], Despite of the low influence of ammonium molybdate on the number of free silicon atoms, a strong variation of the slope is observed. In fact, a weak variation in moles number induces a strong variation on the oligomer number. It can be explained by the size of Si-Mo species creating oligomers which replace the initial Si(OH)4 monomers. The formation of these oligomers inhibits the polycondensation reactions by an effect of oligomer polymerization [8]. 

Organosiloxane oligomers, in silicone polymerization, 22 555-556 Organosiloxane polymers, silicone resins as, 22 586-590... 

Siloxane compounds, in vitreous silica manufacture, 22 414 Siloxane materials, 20 240 Siloxane oligomers, in silicone polymerization, 22 555-556 Siloxanols, silylation and, 22 703 Silsesquioxane hybrids, 13 549 Silsesquioxanes, 15 188, 22 589-590 SilvaGas process, 3 696, 697 Silver (Ag), 22 636-667. See also Silver compounds. See Ag entries Argentothiosulfate complexes Batch desilverizing Lead-silver alloys Palladium-silver alloy membranes analytical methods for, 22 650-651 applications of, 22 636-637, 657-662 as bactericide, 22 656, 657, 660 barium alloys with, 3 344 in bimetallic monetary system, 22 647-648 in cast dental gold alloys, 8 307t coke formation on, 5 266 colloidal precipitation color, 7 343t colloidal suspensions, 7 275 color, 7 334, 335... 

Copolymers of methacrylic add and ethylene termed as ethylene ionomers have been used as the base polymer for binding alkali, alkaline earth and transition metal ions. Organic amines such as n-hexylamine, hexamethylene tetraamine, 2,2,6,6-tetramethyM-hydroxy piperazine, ethylene diamine and polymeric diamines such as silicone diamine, polyether diamine and polymeric diamines such as silicone diamine, polyether diamine and polyamide oligomers considerably enhance the complex formation characteristics of Zn(II) ethylene ionomers thereby enhancing the physico-chemical properties [13]. 

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