Siloxane-silarylene

The synthesis of block polymers of diacetylene-silarylene and diacetylene-carboranylenesiloxane polymers (99a-e) (Fig. 61) by the polycondensation reaction of 1,4-dilithiobutadiyne with l,4-bis(dimethylchlorosilyl) benzene and/or l,7-bis(tetramethylchlorodisiloxane)-m-carborane have been reported by Sundar and Keller.129 These polymers are a hybrid between the carboranylenesiloxane and silarylene-siloxane polymers and have high char yields (up to 85%) at 1000°C in N2 and in air, reflecting the thermal stabilizing effects of the carborane and aromatic units in the polymeric backbone. 

Figure 61 The hybrid silarylene-siloxane/carboranylenesiloxane polymers, 99a-e.

Guida-Pietrasanta, F. and Boutevin, B. Polysilalkylene or Silarylene Siloxanes Said Hybrid Silicones. Vol. 179, pp. 1-27. 

Title High-Temperature Elastomers from Linear Poly(Silarylene-Siloxane-Acetylene)... 

Flexible and oxidatively stable thermosets were prepared by thermally curing linear poly(silarylene-siloxane-acetylene) elastomers at up to 450°C. Thermooxidative weight loss of 3.69% to 7.69% was observed for these crosslinked inorganic-organic hybrid polymers when isothermed at 350°C under air flow. 

Preparation of Hydroxyl Terminated Silarylene-Siloxane Prepolymer... 

TABLE 1. Physical and oxidative stability of poly(silarylene-siloxane-acetylene) elastomers after isothermal curing. 

Figure 2.2. General structures of poly(siloxane) liquid phases. A, poly(siloxane) polymer B, poly(silarylene-siloxane) copolymer and C, a poly(carborane-siloxane) copolymer ( = carbon and O = BH).

Silarylene-disiloxane polymers, which exhibit a wide range of physical properties depending on their composition and structure, have received considerable academic and industrial interest for nearly 50 years.One of the prominent properties of silarylene-disiloxane polymers is their excellent thermal stability. The typical methods employed for the synthesis of silarylene-siloxane polymers are the selfpolycondensation of arylenedisilanols or the copolycondensation of arylenedisila-nols with other bifunctional compounds. We found that the easily accessible 1,4-bis(dimethylsilyl)benzene (p-BSB) could react with water in the presence of a catalytic amount of transition metal (Pd, Pt, Rh, etc.) compounds at room temperature to afford high molecular weight poly[(oxydimethylsilylene)(l,4-phenylene) (dimethylsilylene)] with the evolution of H2 as the only by-product, as shown in Scheme 4.6. ... 

Polysilalkylene or Silarylene Siloxanes Said Hybrid Silicones 3... 

Since the beginning of the 1980s and during the 1990s, Dvornic and Lenz and their co-workers have published numerous articles on the synthesis of silarylene siloxanes and the study of their thermal properties [8-18] ... 

In reference [15], the authors compare four different ways to obtain these hybrid silarylene-siloxane copolymers ... 

Finally, silarylene-siloxane-diacetylene polymers were reported by Hom-righausen and KeUer in 2000 [28], as precursors to high temperatiue elastomers. They were obtained as follows ... 

So, finding a good combination of hybrid or silalkylene siloxanes, classical siloxanes, silarylene siloxanes, preferably fluorinated, remains a challenge to obtain the best elastomer. 

Recent Advances in High-Temperature Network Polymers of Carboranylenesiloxanes and Silarylene-Siloxanes... 

Silarylene-Siloxane Polymers Containing Thermally CrossUnkable... 

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