Deformation Behavior of Sphere-Forming Trifunctional Multigraft Copolymer

Duan, Yongxin; Rettler, Erik F.-J.; Schneider, Konrad; Schlegel, Ralf; Thunga, Mahendra; Weidisch, Roland; Siesler, Heinz W.; Stamm, Manfred; Mays, Jimmy W.; Hadjichristidis, N.

doi:10.1021/ma801036y

Cited by 22 publications

(27 citation statements)

References 22 publications

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“…Such morphology investigation reveals that the PS phase is better dispersed in MG copolymers with higher β value, and the continuity or integrity of PS domains decreases slightly with increasing β, which will decrease the elastic modulus. On the other hand, as shown in Figure 1 and interpreted in our earlier publication, 23 there are two kinds of PI blocks in MG copolymers: PI intermediate blocks and PI end blocks. The PI blocks in all investigated MG copolymers may be assumed to be well-entangled, i.e., M PI_block > 2M e,PI (M e,PI ∼ 4 kg/ mol).…”

Section: Experimental Partmentioning

confidence: 51%

“…In one of our previous communications, 23 the deformation behavior of a trifunctional MG copolymer was examined by synchrotron SAXS and rheo-optical FT-IR at nanometer size scales and molecular level, respectively. On the basis of the finding of the nonaffine deformation and similar orientation behavior of PI and PS segments, it was proposed that the superelasticity is derived from the unique molecular architecture which improves the functionality of PS domains and enhances the stress transfer between PS and PI phases.…”

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confidence: 99%

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Morphology and Deformation Mechanisms and Tensile Properties of Tetrafunctional Multigraft Copolymers

et al. 2009

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Morphology and deformation mechanisms and tensile properties of tetrafunctional multigraft (MG) polystrene-g-polyisoprene (PS-g-PI) copolymers were investigated dependent on PS volume fraction and number of branch points. The combination of various methods such as TEM, real time synchrotron SAXS, rheo-optical FTIR, and tensile tests provides comprehensive information at different dimension levels. TEM and SAXS studies revealed that the number of branch points has no obvious influence on the microphase-separated morphology of tetrafunction MG copolymers with 16 wt % PS. But for tetrafunctional MG copolymers with 25 wt % PS, the size and integrity of PS microdomains decrease with increasing number of branch point. The deformation mechanisms of MG copolymers are highly related to the morphology. Dependent on the microphase-separated morphology and integrity of the PS phase, the straininduced orientation of the PS phase is at different size scales. Polarized FT-IR spectra analysis reveals that, for all investigated MG copolymers, the PI phase shows strain-induced orientation along SD at molecular scale. The proportion of the PI block effectively bridging PS domains controls the tensile properties of the MG copolymers at high strain, while the stress-strain behavior in the low-mediate strain region is controlled by the continuity of PS microdomains. The special molecular architecture, which leads to the higher effective functionality of PS domains and the higher possibility for an individual PI backbone being tethered with a large number of PS domains, is proposed to be the origin of the superelasticity for MG copolymers.

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Section: Experimental Partmentioning

confidence: 51%

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confidence: 99%

Morphology and Deformation Mechanisms and Tensile Properties of Tetrafunctional Multigraft Copolymers

et al. 2009

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“…For this requirement, the glassy spherical microdomains are supposed to be eternally hard. However, it has been suspected that the glassy spheres deformed upon stretching of block copolymer films. − The deformation phenomenon was first detected by Seguela and Prud’homme, in which the deformation of the particle scattering peak was seen in the two-dimensional small-angle X-ray scattering (2d-SAXS) patterns measured for a polystyrene- block -polybutadiene- block -polystyrene triblock copolymer specimen . Although the 20% of the deformation of the particle scattering peak can be seen in this literature, it was not clearly mentioned in the text.…”

Section: Introductionmentioning

confidence: 97%

Strain-Induced Deformation of Glassy Spherical Microdomains in Elastomeric Triblock Copolymer Films: Time-Resolved 2d-SAXS Measurements under Stretched State

et al. 2017

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We have found extremely low efficiency of the elastomeric properties for SEBS (polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene) triblock copolymers having short polystyrene (PS) block chains. Since the SEBS specimens form spherical PS microdomains embedded in the matrix of the rubbery poly(ethylene-co-butylene) (PEB) chains, they exhibit elastomeric properties (thermoplastic elastomer film). However, it was found that the stress was dramatically decreased with time when the specimens were stretched and fixed at strain of 4.0. Furthermore, they showed macroscopic fracture with very short-term duration (400 s to 2 h). To reveal the reason for such low efficiency, we conducted time-resolved two-dimensional small-angle X-ray scattering (2d-SAXS) measurements for the SEBS triblock copolymer films under stretched state at strain of 4.0. Upon stretching, the strain-induced deformation (not fracture) of glassy microdomains was observed. In addition, the deformation of glassy microdomains was found to proceed as time elapsed. Since this deformation of the glassy PS microdomains is considered to result in such the low efficiency of the elastomeric properties, characteristic times related to the deformation and the stress relaxation were evaluated from the change in strain of the glassy microdomains and from the stress relaxation curves, respectively. Then, good agreements of the characteristic times were found, and therefore it was concluded that the deformation of the glassy microdomains has a strong correlation with the stress relaxation and therefore with the fracture of the elastomeric film specimen.

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“…Another technique used to detect the deformation behavior was the FT-IR dichroism method with polarized beam. − Since this method enables evaluation of the polymer chain orientation, it may be also possible to detect the deformation of PS microdomains. Duan et al showed experimental results of SAXS and FT-IR measurements conducted during the stretching of polystyrene- graft -polyisoprene graft copolymer films with PS spherical microdomains. , They concluded the deformation of the PS spheres based on the results of FT-IR measurements showing that the orientation factor of PS block chains increased with strain. However, they failed to clearly detect the particle scattering peak in the 2d-SAXS patterns.…”

Section: Introductionmentioning

confidence: 99%

Strain-Induced Deformation of Glassy Spherical Microdomains in Elastomeric Triblock Copolymer Films: Simultaneous Measurements of a Stress–Strain Curve with 2d-SAXS Patterns

Tomita

Urushihara

et al. 2017

Macromolecules

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Thermoplastic elastomers are elastomeric materials which contain hard domains as physical cross-linking for rubbery chains. Therefore, the hard domains are required permanently rigid. Nevertheless, we have found experimentally deformation of the hard domains upon uniaxial stretching of the thermoplastic elastomer films. In this paper, we report experimental results of deformation of glassy spherical microdomains in elastomeric triblock copolymer films upon uniaxial stretching, as revealed by two-dimensional small-angle X-ray scattering (2d-SAXS) measurements. Actually, shifts of the peak position of the particle scattering toward lower and higher q-regions were detected for q directions parallel and perpendicular to the stretching direction (SD), respectively, where q stands for the scattering vector. By assuming that spheres simply deformed into prolate spheroids with its major axis parallel to SD, 1d-SAXS profiles measured at several strains were successfully reproduced with model calculation of the 1d-SAXS profile. From the results of model calculation, radii of the prolate spheroids were appropriately determined. Since the extent of the deformation of microdomains was found to increase as the initial size of microdomains decreased, it is concluded that the deformation of glassy microdomains may be due to a high extent of the stress concentration at microdomains. Upon unloading, the deformed particle scattering peak in the 2d-SAXS pattern was found to retrieve almost a round shape. At a glance, this fact implies that the deformed sphere (prolate spheroid) recovers an isotropic shape. However, this kind of the elastic behavior cannot be the case for the glassy domain. Alternatively, we have tried to explain the change of the 2d-SAXS pattern by orientational relaxation of the prolate spheroids without changing the shape of the prolate spheroids. It was found that such trial was sound.

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Deformation Behavior of Sphere-Forming Trifunctional Multigraft Copolymer

Cited by 22 publications

References 22 publications

Morphology and Deformation Mechanisms and Tensile Properties of Tetrafunctional Multigraft Copolymers

Morphology and Deformation Mechanisms and Tensile Properties of Tetrafunctional Multigraft Copolymers

Strain-Induced Deformation of Glassy Spherical Microdomains in Elastomeric Triblock Copolymer Films: Time-Resolved 2d-SAXS Measurements under Stretched State

Strain-Induced Deformation of Glassy Spherical Microdomains in Elastomeric Triblock Copolymer Films: Simultaneous Measurements of a Stress–Strain Curve with 2d-SAXS Patterns

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