Synthesis and characterization of poly(silphenylenesiloxane)s containing functional side groups, a study to high-temperature elastomer

Abstract

Poly(silphenylenesiloxane)s containing hydride or vinyl functional side groups were successfully synthesized by deaminative polycondensation of bis(aminosilane)s having the functional groups with monomeric or polymeric bis(silanol). The bis(silanol) prepolymer was prepared by palladium-catalyzed dehydrocoupling polymerization of 1,4-bis(dimethylsilyl)benzene with water. 1 H, 13 C, and 29 Si NMR revealed that the polymers have exactly alternating structure of the starting component units. The poly(silphenylenesiloxane)s containing functional side groups have low T g s ranging from 2 23 to 2 40 8C, and exhibit good thermal stability in both nitrogen and air atmosphere. For example, the most thermally stable polymer 3b-alt, having vinyl side groups on half silicon atoms, has T g at -338C which is 118C lower than that of the all-methyl substituted PTMPS, and shows the highest degradation temperature at 4988C in nitrogen and 5218C in air. The TGA residues at 8008C are 67% in nitrogen and 54% in air. Isothermal studies revealed 3b-alt only lost 2.5% weight after 5h at 4008C in nitrogen. q

Reaction of N-[chloro(diorganyl)silyl]anilines with isopropanol and isopropylamine

“…NMR spectra of compounds III and VI contained signals of siloxanes trace because of the high hydrolytic lability. Chemical shifts of the methyl, vinyl, and phenyl groups in the 1 H and 13 C NMR spectra were close to those for structurally similar Nsilylamines [36][37][38]. IR spectra of silanes I, III, and V-VIII contained the absorption bands of NH groups stretching at 3380-3400 cm -1 .…”

Synthesis of vinyl substitute poly(silphenylene‐siloxane) via silyl hydride‐dialkoxysilane process

“…Vinyl substituted silphenylene siloxane polymers have been synthesized previously using the chlorosilane, 6 ureidosilane, 9,10,35 and diaminosilane 5,6,8,33 routs. The chlorosilane-silanol condensation reaction will generate HCl that can catalyze the self-condensa- tion of the silanol monomer, thus preventing the formation of exactly alternating polymer structures.…”

“…Poly (silphenylene-siloxane) is one kind of candidates for high-temperature polymers that do not generate hazardous gases during thermal decomposition. Polysilphenylene-siloxane is generally prepared by polycondensation of difunctional organosilanes or oligosiloxanes, such as dehydration of 1,4-bis(hydroxydimethylsilyl) benzene (BHSB) and 1,3-bis(hydroxydimethylsilyl)benzene, 3 condensation polymerization of BHSB and bis(dimethylamino)-, [4][5][6][7][8] bisureido-, 9,10 or dichlorodialkylsilanes. 6,11 Dehydrogenative coupling of orgnohydrosilanes and organosilanols or other compounds with active hydrogen such as water is particularly convenient due to its high selectivity and easy removal of the byproduct, hydrogen.…”

“…30 Incorporation vinyl group into the poly(silphenylenesiloxane) molecular demonstrates greatly improved thermal stability with low T g s when compared with the corresponding methyl derivatives. 5,8,32 Furthermore, vinyl substituted poly(silphenylenesiloxane) can easily be crosslinked. The crosslinking density may be controlled over a broad range, depending on the ratio of the crosslinker to the vinyl groups.…”

“…Thus, vinyl substituted polysilphenylenesiloxanes are described to be good candidates of high-temperature elastomers. Vinyl substituted silphenylene siloxane copolymers had been synthesized using the disilanol-diaminosilane and disilanol-dichlorosilane polycondensation methods, 5,6,8,32,33 but have not been synthesized through silyl hydride-dialkoxysilane polycondensation process yet (Scheme 1). Although B(C 6 F 5 ) 3 is also used to catalyze the hydrosilation of alkenes 22 and activate vinylic CÀ ÀH to form vinylborane products, 34 the aim of this work is to disclose whether the vinyl substituted silphenylene siloxane copolymers can be synthesized through the newly developed silyl hydride-dialkoxysilane process while the vinyl group remain undamaged.…”