Separation from linear PDMS

Other examples of successful combinations of liquid chromatography and MALDI-TOF have been reported by Kruger et al. who separated linear and cyclic fractions of polylactides by LC-CC [184]. Just et al. were able to separate cyclic siloxanes from linear silanols and to characterize their chemical composition [185]. The calibration of an SEC system by MALDI-TOF was discussed by Mon-taudo et al. [186]. Poly( dimethyl siloxane) (PDMS) was fractionated by SEC into different molar mass fractions. These fractions were subjected to MALDI-TOF for molar mass determination. The resulting peak maximum molar masses were... 

Based on this procedure Semiyen et al. [63-73] performed extensive studies of isolation and characterization of cyclosiloxanes using improved GL, HPLC, and preparative SEC methods. In addition to isolation and characterization of individual cyclosiloxanes, narrow fractions of cyclic polysiloxanes containing cycles up to DPs of 500 were prepared. Linear chains which were also present in the high molar mass fractions were effectively separated from the rings. In this way the first synthesis of cyclic polymers was achieved [63,64]. Furthermore, perdeuterated PDMS was analyzed [65, 66], polysiloxanes based on (SiMePhO) [67] or (SiHMeO) [68] units, and a so-called paraffm-polysiloxane [69] were studied. Roovers [70] contributed a study of poly(methyl vinyl siloxane). The entire work of Semiyen et al. on cyclic polysiloxanes is described in more than 30 publications and summarized in several book chapters [71-75]. 

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