Synthesis and thermal properties of diphenylsiloxane block copolymers

Yang, Mei‐Hui; Huang, Wu‐Jang; Chien, Tai-Chang; Chen, Ching-Ming; Chang, H. J.; Chang, Yi-Shen; Chou, Chyan

doi:10.1016/s0032-3861(01)00442-6

Cited by 21 publications

(13 citation statements)

References 8 publications

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“…In fact, the nature of the primary transitions of siloxane oligomers, silanols,68 and cyclosiloxanes68 have been exhaustively investigated by several groups 69–76. It has often been reported that siloxane polymers may have a solid–liquid crystalline transition.…”

Section: Resultsmentioning

confidence: 99%

Poly(n‐alkylsilsesquioxane)s: Synthesis, characterization, and modification with poly(dimethylsiloxane)

Prado

Torriani

Yoshida

2010

J. Polym. Sci. A Polym. Chem.

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Self-supported translucent films constituted of poly(n-octylsilsesquioxane) or poly(n-dodecylsilsesquioxane) were obtained from the hydrolysis and condensation of n-octyltriethoxysilane (OTES) or n-dodecyltriethoxysilane (DTES), respectively. Dense films were obtained in the absence of organic solvents, with dibutyltin diacetate as catalyst. These films exhibited good optical transparency and thermal stability. The incorporation of oligomeric dimethylsiloxane units (D Me,Me ) in these materials, derived from silanol-terminated poly(dimethylsiloxane) (PDMS) or 1,1,3,3-tetramethyl-1,3-diethoxydisiloxane (TMDES), was carried out during the hydrolysis and condensation of OTES and DTES and was confirmed by solid-state 29 Si NMR. Poly(n-octylsilsesquioxane) showed a glass-transition temperature at À65 C, due to the increase in the free volume, promoted by the bulky n-octyl groups. The differential scanning calorimetric (DSC) curves of the polymer derived from DTES were characterized by first-order transitions at temperatures ranging from À15.8 to À0.7 C. Further studies of these networks by low-temperature XRD evidenced narrowing of the diffraction halos suggesting a partial order-disorder transition for these materials at lower temperatures. Good thermal stability up to 350 C and the solvent-free production process make these polymers potential candidates for the development of self-supported hydrophobic protective coatings.

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Section: Resultsmentioning

confidence: 99%

Poly(n‐alkylsilsesquioxane)s: Synthesis, characterization, and modification with poly(dimethylsiloxane)

Prado

Torriani

Yoshida

2010

J. Polym. Sci. A Polym. Chem.

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“…The observation of a single T g for each copolymer was consistent with a homogeneous material. The absence of phase separation may be due to the short length of the alternating segments because two distinct thermal transitions have been observed for block copolymers of PDMS and PDPS 40–42. Copolymer XII had a higher T g than XI .…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of alt‐copoly(carbosiloxane)s containing oligodiphenylsiloxane segments

Gädda

Weber

2005

J. Polym. Sci. A Polym. Chem.

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Novel ␣,-divinyloligodiphenylsiloxanes (1,9-divinyldecaphenylpentasiloxane, 1,7-divinyloctaphenyltetrasiloxane, 1,5-divinylhexaphenyltrisiloxane, and 1,3-divinyltetraphenyldisiloxane) were prepared and copolymerized by Pt-catalyzed hydrosilylation with ␣,-dihydridopentasiloxanes. The molecular weights of the copolymers were measured with gel permeation chromatography, and their thermal properties were characterized with differential scanning calorimetry and thermogravimetric analysis. The polymers had high thermal stability in air and nitrogen. The oligomer and polymer structures were determined with 1 H, 13 C, 19 F, and 29 Si NMR and IR spectrometry. The molecular weights of the oligomers were measured with high-resolution mass spectrometry.

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“…PDPS/PDMS block copolymers in which the blocks have sufficient lengths to phase‐separate are expected to have two distinct transitions 7. In our case, however, all copolymers only show a single T g .…”

Section: Resultsmentioning

confidence: 58%

Improvement of anode oxidation reaction of a fuel cell using ammonium formate with Pt‐Ir catalysis

Ohyama

Sugino

Nitta

et al. 2010

Electrical Engineering Japan

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SUMMARYWe have attempted to develop high-performance and safe fuel cells by using ammonium formate as a solid (powder) fuel. This solid fuel has the potential of safer transportability than liquid fuels such as methanol from the viewpoint of toxicity and flammability. In order to make use of some of the advantages of ammonium formate, we investigated the oxidation characteristics of ammonium formate with respect to a Pt electrode. Cyclic voltammograms indicate that ammonium formate has high oxidation activity with respect to a Pt electrode. We have also found that the oxidation of ammonium formate can be improved by the addition of Ir to Pt catalysts. It is highly likely that ammonium formate will be useful as a solid (powder) fuel for polymer electrolyte membrane (PEM) fuel cells. This new fuel will promote the development of safe fuel cells for PEM.

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Synthesis and thermal properties of diphenylsiloxane block copolymers

Cited by 21 publications

References 8 publications

Poly(n‐alkylsilsesquioxane)s: Synthesis, characterization, and modification with poly(dimethylsiloxane)

Poly(n‐alkylsilsesquioxane)s: Synthesis, characterization, and modification with poly(dimethylsiloxane)

Synthesis and characterization of alt‐copoly(carbosiloxane)s containing oligodiphenylsiloxane segments

Improvement of anode oxidation reaction of a fuel cell using ammonium formate with Pt‐Ir catalysis

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