An X-Ray Diffraction Study on Crystalline and Mesomorphic Structures of Poly(diethylsiloxane)

Inomata, Katsuhiro; Yamamoto, Kazami; Nose, Takeru

doi:10.1295/polymj.32.1044

Cited by 9 publications

(10 citation statements)

References 17 publications

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“…The 110 is strong enough to make its second harmonic appear in the pattern, which is a sharp spot toward the beamstop. d spacings for the 110 reflections are about 8 Å (see Table ), which is in agreement with values found in other references. , …”

Section: Resultssupporting

confidence: 91%

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Structural Studies of Extension-Induced Mesophase Formation in Poly(diethylsiloxane) Elastomers: In Situ Synchrotron WAXS and SAXS

Koerner

Luo

et al. 2003

Macromolecules

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Amorphous poly(diethylsiloxane) (PDES) elastomers undergo a transition to an aligned mesomorphic state when subjected to uniaxial tension. The structural changes associated with this transition and the kinetics of its formation have been investigated by in-situ synchrotron wide-angle and small-angle X-ray scattering. In the mesomorphic state, the PDES elastomers are biphasic, consisting of aligned mesophase domains and amorphous material. Because of the well-defined structure of the networks used, we were able to determine that the mesophase domain size is governed by the precursor chain length and is unaffected by trapped entanglements. The observed increase in mesophase content with increase in extension ratio in a fully necked sample is caused by an increase in the number of mesophase domains rather than an increase in domain size. In the extended state, PDES elastomers attain a very high degree of segment orientation comparable to that of mesogen-containing liquid crystalline elastomers.

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Section: Resultssupporting

confidence: 91%

“…d spacings for the 110 reflections are about 8 Å (see Table 1), which is in agreement with values found in other references. 16,17 Degree of Mesophase and Mesophase Formation. Figure 3 shows intensities along horizontal line scans through the middle of the X-ray patterns taken from the images as a function of time.…”

Section: Waxsmentioning

confidence: 99%

Structural Studies of Extension-Induced Mesophase Formation in Poly(diethylsiloxane) Elastomers: In Situ Synchrotron WAXS and SAXS

Koerner

Luo

et al. 2003

Macromolecules

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“…The mesophase of PDMS has been discussed by Ohlberg and Tosaka, , which is a short-range ordered structure and differentiated from the oriented amorphous component. Similar phase structures and mutual transformations were also found in the study of the crystallization behavior of PDES. − ,− …”

Section: Resultssupporting

confidence: 67%

“…During the stretch process without SIC at −45 °C, preferential orientation occurs in the amorphous state first . As strain increases, the mesomorphic phase with disordered conformation eventually forms which may have a structure similar to that of PDES. − The chains of silicon elastomer have a strong nematic interaction and the mesophase is a kind of short-range ordered structure like liquid crystal. − At −50 and −55 °C, SIC of the α form occurs after the generation of mesophase, which is probably assisted with mesophase as the precursor. Note that overstretch also leads to a transition from mesophase to OA structure, during which stretch-induced transition from helix to the extended coil can take place. , At lower temperatures of −60 and −65 °C, the β form is preferred at low strain (ca.…”

Section: Discussionmentioning

confidence: 99%

Stretch-Induced Crystallization and Phase Transitions of Poly(dimethylsiloxane) at Low Temperatures: An in Situ Synchrotron Radiation Wide-Angle X-ray Scattering Study

et al. 2018

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Stretch-induced crystallization (SIC) and phase transitions of poly(dimethylsiloxane) (PDMS) have been studied with the in situ synchrotron radiation wide-angle X-ray scattering technique (WAXS) during tensile deformation at temperatures ranging from −45 to −65 °C. The phase transitions during tensile deformation go through different processes at different temperature regions, where four phases are involved in namely oriented amorphous (OA), mesophase, α form, and β form crystals. We found that SIC of the α form can proceed via two different multistage ordering processes with either the mesophase or β form as the structural intermediate. Further cyclic tensile experiments demonstrate that the transition from the β to α form is a reversible process controlled by stress, which is attributed to the different helical pitches in β and α forms. A nonequilibrium phase diagram of SIC and phase transitions are constructed in strain–temperature space, which is of great significance for practical applications of PDMS at low temperature.

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“…The spinning frequency was 1372 Hz with 5 µs time for the pulse at 90°. The recycling time, D 0 , for the DD-MAS experiments, was 100 s. The cross-polarization wide-line separation (CP-WISE) 1 H/ 29 Si spectra were collected using a 400 WB Bruker Advance spectrometer. The free induction decay (FID) measurements were performed using a sequence of echo pulses at 90°with a duration of 2 µs delayed by 25 µs.…”

Section: Ii1 Materialsmentioning

confidence: 99%

Mesomorphism, Polymorphism, and Semicrystalline Morphology of Poly(Di-n-propylsiloxane)

et al. 2006

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The crystalline structure and semicrystalline morphology of poly(di-n-propyl siloxane), PDPS, were studied with powder and fiber X-ray diffraction, differential scanning calorimetry, solid-state nuclear magnetic resonance and atomic force microscopy (AFM). PDPS exhibits two crystalline phases, α (−45.5 °C < T < 62 °C) and β (T < −45.5 °C), and a hexagonal columnar mesophase which is stable in a broad temperature range between 62 and 197 °C. The low-temperature crystalline phase β is found to be monoclinic with lattice parameters a = 20.60 Å, b = 19.22 Å, c = 4.95 Å, γ = 93.1°. The α crystalline phase has a pseudo-tetragonal unit cell with a = b = 19.15 Å and c = 5.00 Å and is characterized by monoclinic C2/c (No. 15) group symmetry. In the refined unit cell (R wp = 0.127) the PDPS chains adopt a planar cis−trans conformation with the plane of the chain parallel to the b axis. The semicrystalline morphology of the α crystal was studied with AFM. The crystallization of PDPS from the hexagonal mesophase results in very thick (100−150 nm thick) crystalline lamellae, which implies that the chains are fully extended in the crystal. This feature, which is found in few polymers, makes PDPS similar to such systems as HDPE at high pressure or 1,4-trans-poly(butadiene).

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An X-Ray Diffraction Study on Crystalline and Mesomorphic Structures of Poly(diethylsiloxane)

Cited by 9 publications

References 17 publications

Structural Studies of Extension-Induced Mesophase Formation in Poly(diethylsiloxane) Elastomers: In Situ Synchrotron WAXS and SAXS

Structural Studies of Extension-Induced Mesophase Formation in Poly(diethylsiloxane) Elastomers: In Situ Synchrotron WAXS and SAXS

Stretch-Induced Crystallization and Phase Transitions of Poly(dimethylsiloxane) at Low Temperatures: An in Situ Synchrotron Radiation Wide-Angle X-ray Scattering Study

Mesomorphism, Polymorphism, and Semicrystalline Morphology of Poly(Di-n-propylsiloxane)

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