Hydrosilated network polymers

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-... 

Figure 65 The hydrosilated networked polymers 105, 106, and 107 obtained from Karstedt catalyst-catalyzed hydrosilations involving monomeric vinyl- or ethynyl-terminated carboranylenesiloxane and a branched siloxane cross-linker in hexane. The Si-bound methyl groups have been omitted for clarity. (Adapted from ref. 134.)...

The ubiquitous hydrosilation reaction, popular especially in silicone manufacturing,132 has been utilized by Houser and Keller for the synthesis of the networked polymers (104) (Fig. 64) from the reaction of the l,7-bis(vinyltetramethyldisiloxyl)-w-carborane monomer with the polymeric crosslinker, poly(methylhydrosiloxane).133 The reactions were catalyzed by the Speier s catalyst, H2PtCl6. Three samples were... 

Hybrid Siloxane Network Polymers From Hydrosilation Reactions... 

In the interest of producing elastomeric network polymers, Kolel-Veetil et al. reported the modification of the preceding hydrosilation reaction system. They reported the Karstedt catalyst-catalyzed ambient-condition hydrosilation reactions of a monomeric vinyl 14 or ethynyl-containing 17 carboranylenesiloxane with three different monomeric branched siloxane crossUnkers in hexane (Figure 15.19) [36]. The reactions involving the vinylcarboranylenesiloxane were reported to... 

In the case of all of the carboranylenesiloxane network polymers produced either by thermal polymerization or by hydrosilation means, the opportunity exists for their use as neutron absorption materials that may find applications in nuclear reactor shields. The presence of boron atoms in these polymeric materials that are known to be exceptional neutron absorbing species by the well known boron neutron capture (BNC) reaction enhances the importance of them in nuclear applications [70]. 

Finkelmann et al. 256 274,2781 have also investigated the synthesis and the characteristics of siloxane based, crosslinked, liquid crystalline polymers. This new type of materials displays both liquid crystallinity and rubber elasticity. The synthesis of these networks is achieved by the hydrosilation of dimethylsiloxane-(hydrogen, methyl)siloxane copolymers and vinyl terminated mesogenic molecules in the presence of low molecular weight a,co-vinyl terminated dimethylsiloxane crosslinking agents156 ... 

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