Crystalline structure of poly(diaryl siloxanes)

Babchinitser, T.M.; Kazaryan, L.G.; Tartakovskaya, L. M.; Василенко, Н. В.; Zhdanov, A. A.; Коршак, В.В.

doi:10.1016/0032-3861(85)90088-6

Cited by 13 publications

(7 citation statements)

References 4 publications

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“…The last value is usually reported as the intrachain segment distance, whereas the first reflection is related to the distance between the chain segments 12, 34, 42. The first peak is present in so‐called mesomorphic polymeric materials, such as polysilsesquioxanes35, 42, 43 or poly (diphenylsiloxane),44, 45 and its width can be related to the degree of organization of the network 33. This peak became broader for the membranes obtained at higher temperatures (MPP4 and MPP5).…”

Section: Resultsmentioning

confidence: 99%

Partially pyrolyzed poly(dimethylsiloxane)‐based networks: Thermal characterization and evaluation of the gas permeability

José

Prado

Schiavon

et al. 2006

J Polym Sci B Polym Phys

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In this investigation, the preparation and characterization of partially pyrolyzed membranes based on poly(dimethylsiloxane) (PDMS) are described. These membranes were obtained by the crosslinking of silanol‐terminated PDMS with multifunctional nanoclusters derived from the reaction of pentaerythritoltriacrylate with 2‐aminoethyl‐3‐aminopropyltrimethoxysilane and the in situ polycondensation of tetraethylortosilicate, followed by the thermal treatment of the resulting membranes at different temperatures. The partially pyrolyzed membranes were characterized with infrared spectroscopy, thermogravimetry, elemental analyses, dynamic mechanical analysis, small‐angle X‐ray scattering, and scanning electron microscopy. The membranes exhibited improvements in the thermal stability and mechanical strength. Even with distinct compositions with respect to the Si/O and Si/C ratios, the flexibility of these materials was maintained. The flux rates of the gases through the membranes were measured for N2, H2, O2, CH4, and CO2, at 25 °C. The permeability of the membranes changed with increases in the pyrolysis and oxidation temperatures. These membranes could be described as PDMS chains separated by inorganic clusters. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 299–309, 2007.

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Section: Resultsmentioning

confidence: 99%

Partially pyrolyzed poly(dimethylsiloxane)‐based networks: Thermal characterization and evaluation of the gas permeability

José

Prado

Schiavon

et al. 2006

J Polym Sci B Polym Phys

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“…It was shown that polymerization proceeds under heterogeneous conditions; the reaction proceeds inward from the surface of HPTS crystals and leads to the formation of a crystalline polymer, with polymerization and crystallization proceeding sequentially [77]. In this case, the crystallinity of polymerized PDPS samples is inversely proportional to its specific viscosity [78].…”

Section: Influence Of the Structure Of The Initial Organocyclosiloxan...mentioning

confidence: 99%

Ring-Opening Polymerization (ROP) and Catalytic Rearrangement as a Way to Obtain Siloxane Mono- and Telechelics, as Well as Well-Organized Branching Centers: History and Prospects

et al. 2022

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PDMS telechelics are important both in industry and in academic research. They are used both in the free state and as part of copolymers and cross-linked materials. At present, the most important, practically used, and well-studied method for the preparation of such PDMS is diorganosiloxane ring-opening polymerization (ROP) in the presence of nucleophilic or electrophilic initiators. In our brief review, we reviewed the current advances in the field of obtaining polydiorganosiloxane telechelics and monofunctional PDMS, as well as well-organized branching centers by the ROP mechanism and catalytic rearrangement, one of the first and most important reactions in the polymer chemistry of silicones, which remains so at the present time.

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“…An evaluation of the literature with regard to polysiloxanes reveals a wealth of information concerning the phase transitions of polydialkylsiloxanes with several reports focusing on the mesomorphic behavior of polydialkylsiloxanes with n -alkyl side groups. , An additional member of the siloxane family whose morphology and phase transition behavior has received relatively little attention is polydiphenylsiloxane (PDPhS). Presumably this is due to difficulties in synthesizing the high molecular weight polymer, combined with its high crystallinity and intractability that make this particular siloxane especially difficult to characterize. − Dissolution of high molecular weight PDPhS only occurs in high-boiling solvents such as diphenyl ether at temperatures above 150 °C. This greatly limits the evaluation of even the basic properties of the material such as molecular weight and solution properties.…”

Section: Introductionmentioning

confidence: 99%

“…This greatly limits the evaluation of even the basic properties of the material such as molecular weight and solution properties. In an attempt to overcome some of these difficulties, PDPhS has been prepared in which some or all of the phenyl side groups were replaced with tolyl substituents. ,, This modification has the effect of reducing the thermal transition temperatures of the polymer and increasing its solubility in organic solvents, making these materials amenable to solution-state characterization. For pure PDPhS, however, most of the work conducted to date has focused on its bulk properties, yet even these remain to be thoroughly examined.…”

Section: Introductionmentioning

confidence: 99%

Mesomorphic Behavior in Polydiphenylsiloxane. 3. An Examination of High Molecular Weight Polydiphenylsiloxane

et al. 1998

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Polydiphenylsiloxane (PDPhS) has been prepared by solution ring opening polymerization of hexaphenylcyclotrisiloxane and characterized by 29Si solid-state NMR spectroscopy. The thermal characteristics of the polymer have been examined by DSC, dynamic mechanical thermal analysis, linear expansion and X-ray diffraction analysis, and polarized optical microscopy in an attempt to elucidate the nature of the high-temperature mesomorphic phase and understand the high-temperature processing difficulties associated with the material. The results were indicative of a partially ordered molecular structure in the mesomorphic region that is not capable of viscous flow and cannot be ordered by shear. The absence of purely crystalline or purely liquid crystalline behavior is suggestive of a type of intermediate structure for mesomorphic PDPhS.

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Crystalline structure of poly(diaryl siloxanes)

Cited by 13 publications

References 4 publications

Partially pyrolyzed poly(dimethylsiloxane)‐based networks: Thermal characterization and evaluation of the gas permeability

Partially pyrolyzed poly(dimethylsiloxane)‐based networks: Thermal characterization and evaluation of the gas permeability

Ring-Opening Polymerization (ROP) and Catalytic Rearrangement as a Way to Obtain Siloxane Mono- and Telechelics, as Well as Well-Organized Branching Centers: History and Prospects

Mesomorphic Behavior in Polydiphenylsiloxane. 3. An Examination of High Molecular Weight Polydiphenylsiloxane

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