Spinodal decomposition of polymer mixtures with a thermotropic liquid-crystalline polymer as one component

Nakai, Akemi; Shiwaku, Toshio; Hasegawa, Hirokazu; Hashimoto, Takeji

doi:10.1021/ma00166a027

Cited by 71 publications

(45 citation statements)

References 2 publications

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“…First we divided the TEM picture into two regions, one was rich in PCL and the other rich in PCLb-PB, with the help of contrast difference between stained and unstained regions by RuO 4 and the characteristic morphology for the crystallized PCL-b-PB (enclosed, for example, by circles in Figure 2). This picture showed an interconnected periodic structure usually observed at the late stage of spinodal decomposition in polymer blends with a critical composition, 24,25 though the characteristic length in our system was fairly small. The value of was finally evaluated from the statistical average of the periodic length of this structure.…”

Section: Transmission Electron Microscopy (Tem) Observationssupporting

confidence: 51%

“…As a result, the TEM picture divided into two regions showed an interconnected periodic structure usually observed at the late stage of spinodal decomposition in critical polymer blends. 24,25 We evaluated from Figure 2 the characteristic length of composition variation on the basis of Figure 2 and plotted in Figure 3 against phase separation time t p . The time evolution of shows a linear relation in a double logarithmic plot, indicating that a power-law relation, / t p , holds between and t p .…”

Section: Sr-saxs Measurementsmentioning

confidence: 99%

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Effects of Phase Separation on the Crystallization Behavior in a Binary Blend of Poly(ε-caprolactone) Homopolymer and Poly(ε-caprolactone)-block-Polybutadiene Copolymer

Akaba

Nojima

2005

Polym J

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ABSTRACT:The crystallization process of poly("-caprolactone) (PCL) chains in a binary crystalline/crystalline blend, PCL homopolymer and PCL-block-polybutadiene diblock copolymer (PCL-b-PB), has been investigated by synchrotron small-angle X-ray scattering (SR-SAXS) as a function of the characteristic length of composition variation formed by the phase separation between PCL and PCL-b-PB. The temperature range of an UCST-type phase separation overlaps with that of crystallization in this blend, so that the phase separation starts in advance to yield various heterogeneous structures when the blend is quenched from a microphase-separated melt into the crystallization temperature of PCL chains. When < 500 nm the crystallization rate of PCL is equal to that of PCL blocks in PCL-b-PB though there is a large difference in the crystallization rate between neat PCL and PCL blocks. When > 500 nm, on the other hand, the crystallization rate of PCL deviates significantly from that of PCL blocks, and they approach to the values of neat polymers with increasing . The relation between the crystallization rate and the pre-existing composition heterogeneity is quantitatively discussed. [DOI 10.1295/polymj.37.584] KEY WORDS Crystallization / Phase Separation / Crystalline-Amorphous Diblock Copolymer / Binary Blend / Small-Angle X-Ray Scattering / Synchrotron Radiation / It is well known that crystallization is an important factor for morphology formation in polymer blend systems. Many experimental studies on the crystallization behavior and resulting morphology were performed by using completely miscible homopolymer blends, 1-3 because it is easier to understand the crystallization mechanism of such blends in which other factors for morphology formation, such as phase separation between components and microphase separation of block copolymers, are completely excluded. When a binary blend has an UCST-or LCST-type phase separation in a same temperature region of crystallization of constituent polymers, we have to consider a cooperative effect between crystallization and phase separation for the morphology formation, which will be more complicated to understand than the case of miscible blends. However, the interplay between phase separation and crystallization will be more important for the practical purpose, so that many studies have been reported so far on this subject by using binary blends of crystalline/amorphous homopolymers. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] However, a limited number of studies is available on this subject for binary blends of crystalline/crystalline polymers, 20-23 though it might be possible to get more information on the morphology formation because two kinds of crystallization process will be detected.We have previously investigated the morphology formation in a binary blend of poly("-caprolactone) (PCL) and polystyrene, 4,8,9 where an UCST-type phase separation took place at the same temperature range of the PCL crystallization. We used the homogeneous off-critical blends, th...

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Section: Transmission Electron Microscopy (Tem) Observationssupporting

confidence: 51%

Section: Sr-saxs Measurementsmentioning

confidence: 99%

Effects of Phase Separation on the Crystallization Behavior in a Binary Blend of Poly(ε-caprolactone) Homopolymer and Poly(ε-caprolactone)-block-Polybutadiene Copolymer

Akaba

Nojima

2005

Polym J

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“…The phase behavior of b1ends containing a liquid crystalline polymer (LCP) has been widely studied using experimental techniques such as differential scanning calorimetery (DSC), scanning electron microscopy (SEM), small-angle light scattering (SALS), polarized light microscopy (PLM) and X-ray diffraction (XRD) [16][17][18][19][20][21][22][23].…”

Section: Thermodynamic Phase Diagram For Binary Polymer Blends Contaimentioning

confidence: 99%

“…There are many practical difficulties to obtain the blend thermodynamic phase diagram. Therefore, numerous researchers have studied the miscibility behavior of the commercial blend system incorporating LCP copolyesters of poly(ethylene terephthalate) (PET) and p-hydroxybenzoic (PHB) with other engineering thermoplastic polymers [16][17][18][19][21][22][23]. Kimura and Porter [16] used DSC to study the miscibility of blends of PET/PHB with poly(butylene terephthalate) PBT.…”

Section: Thermodynamic Phase Diagram For Binary Polymer Blends Contaimentioning

confidence: 99%

Phase Diagram for Liquid Crystalline Polymer/ Polycarbonate Blends

2003

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A novel mechanism to form binary polymer blends is through phase separation by spinodal decomposition in the unstable region of the phase diagram. The present work investigates the effects of thermally‐induced phase separation by spinodal decomposition on the morphology development of liquid crystalline polymer/polycarbonate blends. Moreover, a thermodynamic binary phase diagram is obtained using a twin‐screw extruder at various processing melt temperatures. Differential scanning calorimetry and scanning electron microscopy were used to study the miscibility of the blends and the resulting morphology. A thermodynamic binary phase diagram exhibiting a lower critical solution temperature was obtained. The droplet size distribution of the blend was also obtained and discussed in light of the Cahn‐Hilliard theory.

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“…Thus, the control of the size of the nuclei and the amplitude of the fluctuations are just opposite of those in NG regime. Since the mid-seventies, many authors have studied SD by wide and small angle light scattering (WALS and SALS, respectively) [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], by optical microscope (OM) [22][23][24][25][26][27][28][29][30][31], by pulsed nuclear magnetic resonance (NMR) [29], by small angle neutron scattering (SANS) [31], and by small angle X-ray scattering (SAXS) [32]. In this paper the main attention is paid for WALS, SALS, and OM.…”

Section: Introductionmentioning

confidence: 99%

Interdiffusion and Spinodal Decomposition in Electrically Conducting Polymer Blends

Takala

Seppälä

et al. 2015

Polymers

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Abstract:The impact of phase morphology in electrically conducting polymer composites has become essential for the efficiency of the various functional applications, in which the continuity of the electroactive paths in multicomponent systems is essential. For instance in bulk heterojunction organic solar cells, where the light-induced electron transfer through photon absorption creating excitons (electron-hole pairs), the control of diffusion of the spatially localized excitons and their dissociation at the interface and the effective collection of holes and electrons, all depend on the surface area, domain sizes, and connectivity in these organic semiconductor blends. We have used a model semiconductor polymer blend with defined miscibility to investigate the phase separation kinetics and the formation of connected pathways. Temperature jump experiments were applied from a miscible region of semiconducting poly(alkylthiophene) (PAT) blends with ethylenevinylacetate-elastomers (EVA) and the kinetics at the early stages of phase separation were evaluated in order to establish bicontinuous phase morphology via spinodal decomposition. The diffusion in the blend was followed by two methods: first during a miscible phase separating into two phases: from the measurement of the spinodal decomposition. Secondly the diffusion was measured by monitoring the interdiffusion of PAT film into the EVA film at elected temperatures and eventually compared the temperature dependent diffusion characteristics. With this first quantitative evaluation of the spinodal decomposition as well as the interdiffusion in conducting polymer blends, we show that a systematic control of the phase OPEN ACCESSPolymers 2015, 7 1411 separation kinetics in a polymer blend with one of the components being electrically conducting polymer can be used to optimize the morphology.

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Spinodal decomposition of polymer mixtures with a thermotropic liquid-crystalline polymer as one component

Cited by 71 publications

References 2 publications

Effects of Phase Separation on the Crystallization Behavior in a Binary Blend of Poly(ε-caprolactone) Homopolymer and Poly(ε-caprolactone)-block-Polybutadiene Copolymer

Effects of Phase Separation on the Crystallization Behavior in a Binary Blend of Poly(ε-caprolactone) Homopolymer and Poly(ε-caprolactone)-block-Polybutadiene Copolymer

Phase Diagram for Liquid Crystalline Polymer/ Polycarbonate Blends

Interdiffusion and Spinodal Decomposition in Electrically Conducting Polymer Blends

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