So-called "ladder structure" of equilibrated phenylsilsesquioxane

Frye, Cecil L.; Klosowski, J.

doi:10.1021/ja00747a047

Cited by 94 publications

(57 citation statements)

References 2 publications

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“…On the other hand, with respect to the polysilsesquioxane ladder, Brown et al [13] first reported the synthesis of a soluble polyphenylsilsesquioxane ladder by means of an "equilibration polymerization" method in 1960. However, his result was refuted 11 years later by Frye et al, [14] who pointed out that the polyphenylsilsesquioxane ladder is not a complete ladderlike polymer, but "partially opened polycyclic cages". In 2004, Yamamoto et al [15] reported an oligomeric polyphenylsilsesquioxane ladder with low ladder regularity.…”

Section: Introductionmentioning

confidence: 95%

Supramolecular Template‐Directed Synthesis of Perfect Phenelenediimino‐Bridged Ladderlike Polyphenylsiloxanes

Zhang

Deng

Zhang

et al. 2006

Chemistry A European J

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A template synthesis of the soluble, high molecular weight (Mw), and perfect p-phenylenediimino (p-PDA)-bridged ladderlike polyphenylsiloxane (PLPS) is reported. First, N,N'-bis(phenyldichlorosilyl)-p-PDA monomers were self-assembled into a perfect ladder superstructure (LS) by concerted interaction of aromatic pi-pi stacking and hydrogen bonding. Then the LS underwent a novel stoichiometric hydrolysis/dehydrochlorination-condensation reaction instead of the usual hydrolysis/dehydration-condensation reaction, leading to the PLPS. The perfect ladder structures of both the PLPS and, in particular, the unstable supramolecular LS were confirmed as follows. 1) There are two Bragg peaks in solid and/or solution X-ray diffraction (XRD) spectra representing the ladder width (w) and ladder thickness (t); these peaks were consistent with those calculated by molecular simulation. 2) Both the PLPS and LS have extremely sharp absorption peaks with small half-peak widths (Delta(1/2) < 0.3 ppm) in 29Si NMR spectra, suggesting the presence of the perfect ladder structure for PLPS and LS. 3) Moreover, no noticeable absorption peaks for the Si-OH and NH2 groups were observed in FT-IR and 29Si NMR spectra, indicating that the Si-N bond of the [triple bond]Si-NH-C6H4-NH-Si[triple bond] ladder rung of PLPS and LS is not cleaved. 4) Both PLPS and LS show similar emission peaks (in fluorescence spectroscopy) attributed to the excimer formed by face-to face pi-pi stacking of phenyl groups along the ladder chain rather than a branched direction. 5) Differential scanning calorimetry (DSC) measurements indicate a high glass temperature (Tg = 176.4 degrees C) for PLPS. As circumstantial evidence, this result further indicates very high stiffness of PLPSs ladder backbone as compared with flexible single-chain polyphenylmethylsiloxane with a low Tg = -69.4 degrees C.

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Section: Introductionmentioning

confidence: 95%

Supramolecular Template‐Directed Synthesis of Perfect Phenelenediimino‐Bridged Ladderlike Polyphenylsiloxanes

Zhang

Deng

Zhang

et al. 2006

Chemistry A European J

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“…1 Its unique double-chain ladderlike structure, which results in film-forming ability, thermal stability and mechanical property, and so forth, different from those of more classical polymers, has interested many polymer chemists. [2][3][4][5][6][7][8][9] However, this polymerization method cannot be used to synthesize reactive ladderlike polysilsesquioxanes such as ladderlike polyhydrosilsesquioxane (H-T) and polyvinyl(or allyl)silsesquioxane (Vi-T or Allyl-T) due to its harsh reaction conditions (at 250°C in the presence of KOH).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of a novel reactive ladderlike 4,4?-phenylene ether-bridged polyvinylsiloxane

Liu

Zhao

Xie

et al. 2000

J. Polym. Sci. A Polym. Chem.

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“…Because of their solubility, ladder structures have been proposed 123. However, viscosity studies by Frye [3] indicate that the polyphenylsilsesquioxane is more likely best represented by a polymer rich in both cyclic structures and branches, but without any regular stereochemistry.…”

Section: Introductionmentioning

confidence: 99%

Preparation and characterization of aryl-substituted polysilsesquioxanes

Schneider¹,

Loy²,

Baugher³

et al. 1998

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Polymerizations of aryltrialkoxysilanes generally afford soluble oligomeric or polymeric arylsubstituted silsesquioxanes. This is in spite of being based on trifunctional precursors capable of forming highly crosslinked and insoluble network polymers. In this study, soluble phenyl, benzyl, and phenethyl-substituted silsesquioxane oligomers and polymers were prepared by hydrolyzing their respective triethoxysilyl precursor with water or aqueous acid. Additional samples of the polymers were prepared by heating the materials at 100 "C or 200 "C under vacuum in order to drive the condensation chemistry. One sample of polybenzylsilsesquioxane was heated at 200 "C with catalytic NaOH. The resulting materials were characterized using solution 'H, I3C, and 29Si NMR spectroscopy, gel permeation chromatography, and differential scanning calorimetry. Of particular interest was the effect of the aryl substituent, and processing conditions on the molecular weight and glass transition temperatures of the polysilsesquioxanes.

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So-called "ladder structure" of equilibrated phenylsilsesquioxane

Abstract: Table . Metal-Promoted Isomerizations of l-Methyltricyclo[4. .1.0.0* '7]heptane Catalyst Conditions temp, time, solvent a ch3 11 -% yield of products-,ch3 cc d ch3 12 13 CH, 'to 14 [Rh(CO)iCl]i 25°, 15 min, CHC1, 96 [Ir(CO)sCl]i 25°, 14 hr, CHC1, 93

Cited by 94 publications

References 2 publications

Supramolecular Template‐Directed Synthesis of Perfect Phenelenediimino‐Bridged Ladderlike Polyphenylsiloxanes

Supramolecular Template‐Directed Synthesis of Perfect Phenelenediimino‐Bridged Ladderlike Polyphenylsiloxanes

Synthesis and characterization of a novel reactive ladderlike 4,4?-phenylene ether-bridged polyvinylsiloxane

Preparation and characterization of aryl-substituted polysilsesquioxanes

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