Siloxane-type polymers block copolymers

We have a specific interest in the self-assembled structures formed by poly(ferrocenylsilane) block copolymers, such as poly(ferrocenyldimethylsilane-Z -dimethyl-siloxane) (PFS-PDMS) and (ferrocenyldimethylsilane-Z>-isoprene) (PFS-PI). The PFS block contains an iron atom in the main chain repeat unit. These polymers are particularly promising for novel applications, since they can be used as charge-transport materials and, by pyrolysis, as precursors to ferromagnetic ceramics [4-6], Moreover, they can by synthesized with a very narrow molar mass distribution, with excellent control over chain length and composition [7], An important feature of PFS is that the polymers bearing two methyl groups on the silane unit are crystalline, whereas polymers with two different substituents on each silane (methyl, ethyl methyl, phenyl) are atactic and remain amorphous. This feature of the polymer composition has a strong influence on the type of self assembled structures that these poly-... 

Omega-SLllyl polycarbonates have been hydrosilated with either tertiary silanes or ym-tetramethyldisiloxane to yield silylated polycarbonates or polycarbonate-disiloxane-polycarbonate triblock copolymers.The siloxane-containing polymers exhibit relatively lower Tg and higher thermooxidative stability compared with bisphenol A polycarbonate. Hydrosilation of allyl-terminal poly(alkyleneoxide-co-sulfone) in 1 1 or 2 1 ratio with hydride-terminal polysiloxane leads to ABC and (AB)2C type block-terpolymers, respectively. DSC studies indicate microphase separation, while TGA data point to higher thermal stability for the siloxane... 

Thermoplastic perfluorocyclobutane arylene ether polymers offer a solvent soluble, melt processable, low dielectric alternative to conventional fluoropolymers. Relatively little time has been spent on their development, however. The bifimctional monomers have proven quite useful as comonomers in modifying the thermal and mechanical properties of high Tg thermoset copolymers. In particular, the siloxane PFCB polymer discussed earlier (Figure 3) exhibits a Tg = 16 C (DSC) thereby providing a reactive toughening or flexibilizing additive either as block type copolymers or comonomer for random incorporation (8),... 

X HE IMPORTANCE AND UTILITY of multiphase copolymer systems have been well documented in the literature (1-4), with emphasis on their unique combination of properties and their potential material applications. Or-ganosiloxane block polymers are a particularly interesting type of multiphase copolymer system because of the unusual characteristics of poly siloxanes, such as their stability to heat and UV radiation, low glass transition temperature, high gas permeability, and low surface energy (i, 2, 5). The incorporation of polysiloxanes into various engineering polymers offers an opportunity for many improvements, such as lower temperatures for the ductile-to-brittle transitions and improved impact strength. 

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