Trifluoropropylmethyl-polysiloxane

Product analysis was carried out by a SIEMENS gas chromatograph PGC302-II, equipped with a crossbond trifluoropropylmethyl polysiloxane column 105 m long, 0.53 mm ID, 3.0 pm df (RTX-200, RESTEK GmbH) and TC detector. 

Substrates and reduction products were identified on a Hewlett Packard HP6890 gas chromatograph equipped with an FID detector and employing a 30m Restek RTX-200 eapillary column (trifluoropropylmethyl polysiloxane pacing). Yields of the resulting alcohols from these reductions were based on area percents correlated to known quantities of high purity standards (Aldrich). 

Figure 5.24 shows the high-speed separation of a 20-component pesticide mixture (plus one impurity peak). The 14-m-long, 0.18-imn-i.d. thin film column ensemble consists of 7.0 m of a trifluoropropylmethyl polysiloxane column followed 7.0 m of 5% phenyl dimethyl polysiloxane column segment. For chromatogram (a), no stop-flow pulses were used, and component pairs 2,3 and 10,11 coelute. For chromatogram (b), a single 2-s wide stop-flow pulse was used to enhance the resolution of peak pair 2,3. Note that the peak pattern and resolution... 

The dual-column ensemble will consist of two 3.0-m-long microfabricated columns, one using a nonpolar dimethyl polysiloxane stationary phase (see Figure 5.27) and the other using a moderately polar trifluoropropylmethyl polysiloxane stationary phase. The column ensemble can be operated in the stop-flow mode by the use of a valve between the preconcentrator and the column junction point. Detection is provided by an array of microfabricated chemiresistor sensors, each having a different selectivity. The pattern of responses from the varions sensors will be nsed for vapor recognition and the quantitative analysis of overlapping peaks. 

Detailed information on the copolymerization of cyclic trifluoropropylmethyl-siloxane trimer and octamethylcyclotetrasiloxane is also very limited in the open literature26 27 . Recently, preparation of various amine terminated (dimethyl-tri-fluoropropyl,methyl)siloxane oligomers with varying molecular weights and backbone compositions has been reported 69115 ll7). Table 11 shows various properties of the oligomers produced as a function of composition. These types of modification play very important roles in determining the solubility characteristics and hence the compatibility of resultant polysiloxanes with other conventional organic monomers... 

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