Silphenylene polymers crystallinity

Partial replacement of siloxane units with silphenylene groups also increases polymer crystallinity (5, 6), results in a higher viscosity (7), increases the mechanical properties, and improves thermal stability. On the other hand, incorporation of the rigid silphenylene units into the poly siloxane backbones could decrease the low-temperature elasticity of these polymers (8). 

Insertion of a silphenylene group [-Si(CH3)2C6H4-] into the backbone of the PDMS repeat unit yields either the siloxane meta and para silphenylene polymers (32-38). The Tg of the former polymer is increased to -48 C, but no crystallinity has been... 

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