Spirosiloxanes as Monomers for the Photo-Induced Polymerization to Polysiloxane Architectures

SPIROSILOXANES AS MONOMERS FOR THE PHOTO-INDUCED POLYMERIZATION TO POLYSILOXANE ARCHITECTURES 

Polysiloxanes gain more and more interest in recent years due to their excellent chemical and physical properties, such as thermal stability, hydrophobicity or electrical resistance (1). One synthesis route towards linear polymers is the ROP of cyclic monomers such as hexamethylcyclotrisiloxane (D3) (2). The functionalization of the substituents on the silicon atom in the polymer is performed via the modification of the cyclic monomers. Especially vinylic side groups are often introduced into the polymer backbone since they are active groups for cross-linking of polysiloxanes to three dimensional networks such as silicone elastomers (3). 

Three-necked 500 mL Schlenk flask, dropping funnel, reflux condenser, Schlenk tube, Schlenk frit, vacuum distillation apparatus, magnetic stirrer, safety glasses, protective gloves, and laboratory coat. 

2-Methyl-4-en-2-ol, 1-methylimidazole, dichlorosilane, diethyl ether, acetone, dry ice. 

The complete reaction was performed under Schlenk conditions. Dry diethyl ether (250 mL) was placed in 500 mL Schlenk three-necked flask equipped with a dropping funnel and reflux condenser. The dropping funnel was charged with a mixture of 31.9 g (389 mmol, 2 equiv) 1-methylimidazole and 38.9 g (389 mmol, 2 equiv) 2-methylpent-4-en-2-ol in 50 mL diethyl ether. One quarter of the prepared mixture was added to the diethyl ether. The 19.6 g (194 mmol, 1 equiv) dichlorosilane condensed into a Schlenk tube at -78°C were allowed to slowly diffuse into the stirred reaction mixture at —78°C. Meanwhile the residual mixture from the dropping funnel was slowly added to the reaction mixture which is then stirred for a further 10 h at room temperature. The resulting methylimidazole hydrochloride was removed by filtration through a Schlenk frit and the solvent was evaporated imder reduced pressure (200 mbar). After fractionated condensation in vacuo (0.3 mbar, 60°C) 35.7 g (156 mmol, 81%) bis((2-methylpent-4-en-2-yl)oxy)silane were obtained as a colorless liquid. 

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Spirosiloxanes as Monomers for the Photo-Induced Polymerization to Polysiloxane Architectures 290... 

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