Physical characteristic, linear oligomers

These anionic ring opening polymerizations are usually carried out either in bulk or in solution. A host of catalyst types are active. For synthetic references using specific catalysts, the reader is referred to several excellent sources (4,7,31,32). Representative catalysts include hydroxides, alcoholates, phenolates, silanolates, siloxanolates, mercaptides of the alkali metals, organolithium and potassium compounds, and quaternary ammonium and phosphonium bases and their silanolates and siloxanolates. Some physical characteristics of linear oligomers are given in Table 5 (10). 

TABLE 5. SOME PHYSICAL CHARACTERISTICS OF LINEAR OLIGOMERS... 

Table 6.11 shows the results of elementary analysis, physical chemical properties and the yield of ethylsiloxane oligomers containing cyclic fragments in the side chain. In the IR spectra of oligomers with cyclic fragments in the side chain one can observe the absorption bands characteristic of asymmetric valence oscillations of the =Si-0-Sis bonds in the region 1020 and 1080 cm characteristic of both linear siloxane links and cyclosiloxane rings. In the IR spectra one can also observe absorption bands for unreacted =Si-H bonds at 2160 cm. ... 

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