Methylsiloxane oligomers

Thus, for the first time methylsiloxane oligomers and copolymers with various cyclic fragments in the side chain were synthesised by us and it was shown that cyclic fragments in the side chain behave in thermal destruction processes as cyclic fragment in the main chain. 

Figure 9.17 Capillary SFC separation of methylsiloxane oligomers (Dow Corning DC 200 Fluid). Conditions 27m x 50/im I.D. SE-54 (dfO.lSfim), CO2 at 40°C and density programmed from 0.3gcm" (15min) to 0.8gcm at 0.0075gcmmin[6]. Reprinted with permission from Anal. Chem. 56, 619A, 1984 American Chemical Society.

POLYFUNCTIONAL METHYLSILOXANE OLIGOMERS WITH GLYCIDOXYPROPYL SIDE GROUPS... 

Liquid polydimethylsiloxanes are stable up to 175 °C, whereas liquid polyphenyl-methylsiloxanes are stable up to 300 °C. Polydimethylsiloxane (PDMS) decomposes under vacuum at 400 °C to form the cyclic oligomers hexamethylycyclotrisiloxane and oxamethylcyclotetrasiloxane. This process occurs at lower temperatures in the presence of terminal Si-OH groups or additives of electrophilic or nucleophilic character. The terminal OH groups interact with the Si-0 bond by the scheme ... 

The equilibrium ROP of cydosiloxanes has also some limitations. The main restraint concerns the formation of cydic oligomers. Since the polymer yield in equilibrium depends dramatically on the size and polarity of substituents at silicon, the process is usually applied to the s)mthesis of dimethylsiloxane and methylsiloxane polymers and (their) copolymers. The equilibrium ROP is carried out in bulk as the dilution of the system favors formation of cyclics. The reartion cannot be used for the synthesis of polysiloxanes with a narrow MW... 

Side chain liquid crystalline oligomers were synthesized in order to obtain a more detailed understanding of the change in phase behavior in going from the monomer to the polymer. One study involved monodisperse oligo(methylsiloxane)s with mesogenic side chains (28). ... 

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