• Title/Summary/Keyword: Polycarbosilanes

Search Result 6, Processing Time 0.017 seconds

Synthesis and Properties of Conjugated Polycarbosilanes with 1,4-Bis(thiophene or phenylene)-buta-1,3-diyne

  • 서일권;박영태;김용록
    • Bulletin of the Korean Chemical Society
    • /
    • v.20 no.6
    • /
    • pp.677-682
    • /
    • 1999
  • Conjugated polycarbosilanes with diacetylene and aromatic groups of thiophene or phenylene simultaneously present in the polymer backbone such as poly[[1,4-bis(thiophenyl)buta-1,3-diyne]-alt-(dimethylsilane)], poly[[1,4-bis(thiophenyl)buta-1,3-diyne]-alt-(diphenylsilane)], poly[[1,4-bis(phenyl)buta-1,3-diyne]-alt-(dimethylsilane)],and poly[[1,4-bis(phenyl)buta-1,3-diyne]-alt-(diphenylsilane)] have been prepared. The characteristic C=C stretching frequencies appear at 2177-2179㎝-1 in the IR spectra of the polymers. The molecular weights of these polymers were detemined by GPC. All of these materials are soluble in organic solvents such as THF and chloroform, and thermally stable up to 200℃ in general without any weight loss under nitrogen. The prepared materials in THF solvent show a maximum absorption peak in the range of 334-356 nm with a molar absorptivity of 10³∼10ⁿ(n=5)L/(cm·mol) in the UV-visible absorption spectra. A maximum emission peak in the range of 403-550 nm is also observed in the fluorescence emission spectra. Both absorption and emission spectra strongly indicate that the obtained polycarbosilanes contain the new conjugated systems along the polymer main chain.

Oxidative Coupling Polymerization of Diethynylsilane Derivatives and 1,2-Diethynyl-1,1,2,2-tetramethyldisilane

  • Kim, Ji-Ho;Park, Young-Tae
    • Bulletin of the Korean Chemical Society
    • /
    • v.27 no.6
    • /
    • pp.869-874
    • /
    • 2006
  • We have carried out the Glaser oxidative coupling polymerizations of diethynyldiphenylsilane, diethynylmethylphenylsilane,diethynylmethyloctylsilane, and 1,2-diethynyl-1,1,2,2-tetramethyldisilane to afford polycarbosilanes containing diethynyl and organosilane groups in the main chain, such as poly(diethynyldiphenylsilane), poly(diethynylmethylphenylsilane), poly(diethynylmethyloctylsilane), and poly(1,2-diethynyl-1,1,2,2-tetramethyldisilane), respectively. These obtained materials are almost insoluble in common organic solvents such as $CHCl_3$ and THF probably due to the presence of a rigid rod diacetylene group along the polymer main chain. Therefore, the polymers were characterized using several spectroscopic methods in solid state. FTIR spectra of all the polymeric materials show that the characteristic $C \equiv C$ stretching frequencies appear at 2147-2154 $cm ^{-1}$, in particular. The polymers in the solid state exhibit that the strong maximum excitation peaks appear at 260-283 nm and the strong maximum fluorescence emission bands at 367-412 nm, especially. Thermogravimetric analysis of the materials shows that about 55-68% of the initial polymer weights remain at 400 ${^{\circ}C}$ in nitrogen.

Synthesis and Properties of Poly(1,1-diethynyl-1-silacyclopent-3-enes and -1-silacyclobutane)

  • Kim, Eun-Joo;Park, Jung-Woo;Kim, Yong-Rok;Park, Young-Tae
    • Bulletin of the Korean Chemical Society
    • /
    • v.24 no.4
    • /
    • pp.484-488
    • /
    • 2003
  • Polycarbosilanes containing diacetylene and organosilacyclic groups, such as poly(1,1-diethynyl-1-silacyclopent-3-ene), poly(1,1-diethynyl-3-triethylsilyl-1-silacyclopent-3-ene), and poly(1,1-diethynyl-1- silacyclobutane), were synthesized by the Glaser oxidative coupling polymerization reactions of 1,1-diethynyl-1-silacyclopent-3-ene, 1,1-diethynyl-3-triethylsilyl-1-silacyclopent-3-ene, and 1,1-diethynyl-1-silacyclobutane, respectively. These materials are almost insoluble in usual organic solvents such as $CHCl_3$ and THF. The polymers were characterized by using several spectroscopic methods in solid state. FTIR spectra of all the polymeric materials show that the characteristic C≡C stretching frequencies appear at 2146-2170 $cm^{-1}$, in particular. The polymers in the solid state show that the strong maximum excitation peaks appear at 255-257 nm and the strong maximum fluorescence emission bands at 401-402 nm. About 71-87% of the initial polymer weights remain at 400 ℃ in nitrogen according to thermogravimetric analysis.

Characterization of SiC Fiber Derived from Polycarbosilanes with Controlled Molecular Weight (분자량이 조절된 폴리카보실란으로부터 제조한 SiC Fiber의 특성분석)

  • Shin, Dong-Geun;Riu, Doh-Hyung;Kim, Younghee;Kim, Hyung-Rae;Park, Hong-Sik;Kim, Hyoun-Ee
    • Journal of the Korean Ceramic Society
    • /
    • v.42 no.8 s.279
    • /
    • pp.593-598
    • /
    • 2005
  • Polycarbosilane was synthesized by the Kumada rearrangement of polydimethylsilane in the presence of zeolite (ZSM-5) as a catalyst at $350^{\circ}C$. The prepared polycarbosilane had very low molecular weight ($M_w=500$), so that it was not suitable to fabricate SiC fiber by melt spinning. Further polymerization of PCS was conducted around $400^{\circ}C$ to obtain spinnable polycarbosilane. After polymerization, the polycarbosilanes were isolated by distillation according to the molecular weight distributions. The PCS with a controlled molecular weight distribution was spun into continuous polycarbosilane green fibers. The PCS green fiber was successfully transformed into silicon oxycarbide fiber. The room temperature strength of the SiC fiber was around 1.5 - 1.8 GPa. The oxidation behavior and the tensile strength after oxidation were also evaluated.

Synthesis of Dendritic Carbosilanes by the Use of Hyperbranched Polymers (Hyperbranched Polymer를 이용한 나뭇가지꼴 카보실란 거대분자의 합성)

  • Kim, Chung Kyun;Kang, Sung Kyung;Park, Eun Mi
    • Journal of the Korean Chemical Society
    • /
    • v.43 no.4
    • /
    • pp.393-400
    • /
    • 1999
  • Dendritic carbosilanes based on hyperbranched polycarbosilanes as core molecule have been prepared The core molecules were obtained by the use of hydrosilation of $HSiMe_{3-n}$$(CH_2CH=CH_2)_n$(n=2; $AB_2$,3;$AB_3$type). The hyperbranched core $AB_2\;and\; AB_3$ type polymers were generated to higher molecular dendritic carbosilanes Gn+1 by the use of hydrosilation and alkenylation sequence. The Gn+2P generations were not obtained as unified molecules by the use of hydrosilation with $HSiMeCl_2$. Gn and Gn+1 type polymers were produced to polysilol by the reaction of 9-BBN and alkali medium oxidation of hydroborated compounds. The degree for reaction has been controlled by the NMR spectroscopy.

  • PDF