Carboranylenesiloxane monomers

Hybrid Siloxane Network Polymers From HydrosUation Reactions of Siloxane and Carboranylenesiloxane Monomers... 

Figure 15.19 The carboranylenesiloxane monomers and the branched sUoxane crosslinkers used in the hydrosUation reactions reported by Kolel-Veetil et al.

Recently, Kolel-Veetil and Keller have modified this system to produce elastomeric networked polymers. The ambient-condition hydrosilation reactions between monomeric vinyl- or ethynyl-terminated carboranylenesiloxane and three different monomeric branched siloxane cross-linkers in hexane yielding these systems were catalyzed by the Karstedt catalyst.134 The reactions involving the vinyl-carboranylenesiloxane were reported to produce a set of completely hydrosilated networked polymers (105) (Fig. 65). In the case of the ethynyl monomer, the reactions were carried out at two different ratios, yielding a partially (106) and a com-... 

The linear polymers were readily formed by both methods. A salient feature in both of the syntheses was the in situ production of a desired carboranylenesiloxane oligomer by the reaction of a lithiated carborane and a chlorinated siloxane species rather than the use of the commercial Dexsil monomer as in the case of Henderson et al. [25] and Houser et al. [29], This has afforded an enormous degree of variation in the compositions of diacetylene-containing carboranylenesiloxane polymers that is not available by the conventional route of Henderson et al. [25]. The effect of the reduction in the diacetylene concentration was apparent in the positions and the intensities of the DSC peak maxima of the crossUnking endotherms of 5a-c. Thus, it was observed that as the concentration of the diacetylene units in the polymer... 

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