The percolation-to-cluster transition during spinodal decomposition of an off-critical polymer mixture. Observation by light scattering and optical microscopy

Läuger, Jörg; Lay, R.; Gronski, W.

doi:10.1063/1.468304

Cited by 42 publications

(60 citation statements)

References 5 publications

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“…[25,36,48] It is therefore remarkable that spinodal structures with unequal phase fractions are known to disintegrate during coarsening. [49,50] For NPG this implies that networks with low ϕ may exhibit a reduced connectivity density of their load-bearing paths, which would make them anomalously weak and compliant.…”

Section: Role Of Network Connectivity?mentioning

confidence: 99%

Nanoporous Gold—Testing Macro-scale Samples to Probe Small-scale Mechanical Behavior

Mameka¹,

Wang

Markmann

et al. 2015

Materials Research Letters

121

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Nanoporous gold made by dealloying exemplifies how the exciting mechanical properties of nanoscale objects can be exploited in designing materials from which macroscopic things can be formed. The homogeneous microstructure and the possibility of adjusting the ligament size, L, between few and few hundred nm, along with the high deformability and reproducible mechanical behavior predestine the material for model studies of small-scale plasticity using reliable macroscopic testing schemes on mm-or cm-size samples. Such experiments tend to agree with the Gibson-Ashby scaling relation for strength versus solid fraction, while suggesting an essentially L −1 scaling of the local strength of the ligaments. By contrast, the elastic compliance is dramatically enhanced compared to the Gibson-Ashby relation for the stiffness. Contrary to intuition, the anomalously compliant behavior of the nanomaterial goes along with a trend for more stiffness at smaller L. This article discusses surface excess elasticity, nonlinear elastic behavior and specifically shear instability of the bulk, network connectivity, and the surface chemistry as relevant issues which deserve further study.

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Section: Role Of Network Connectivity?mentioning

confidence: 99%

Nanoporous Gold—Testing Macro-scale Samples to Probe Small-scale Mechanical Behavior

Mameka¹,

Wang

Markmann

et al. 2015

Materials Research Letters

121

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“…gravity). Polymer blends in which pinning has recently been observed for offcritical composition include X-7G/poly(ethylene teraphthalate) (a liquid crystalline polymer/homopolymer blend) [1], poly(styrene-ran-butadiene)/polybutadiene [4], poly(styreneran-butadiene)/polyisoprene [4], and polybutadiene/polyisoprene [6].…”

Section: Introductionmentioning

confidence: 99%

“…Experiments on spinodal decomposition in polymer blends show that the coarsening process may sometimes slow dramatically or even cease before reaching equilibrium [1] - [6]. In these systems, spinodal decomposition -which is the process by which a thermodynamically unstable mixture demixes to a stable, phase-separated equilibrium state [7] - [13] -proceeds normally for some time following a quench to the unstable region (T < T s ), and then stops.…”

Section: Introductionmentioning

confidence: 99%

On the mechanism of pinning in phase-separating polymer blends

Castellano

Glotzer

1995

The Journal of Chemical Physics

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“…The percolating, bicontinuous phase structure originating in spinodal decomposition is generally said to develop rapidly by hydrodynamic coarsening, in cases where the characteristic length of the structure develops linearly with time. 17 In the TPE/oil system, hydrodynamic flow may be the major mechanism of structurecoarsening in the initial stage at which D ∝ t. Now we consider the late stage, where D ∝ t 1/3 . Figure 8 shows the optical micrographs of phase separation in a very late stage at 60 • C. The coarsening process is easily observed, since it proceeds slowly at around the 70 min after the onset of phase separation.…”

Section: Alteration Of Time-evolution Of Phase Separationmentioning

confidence: 99%

“…The study also proposed that such pinning might originate in a kinetic barrier that suppresses the diffusion of polymer-molecules. After the initial report of Hashimoto, Gronski et al 17 studied the PC transition by optical micrographs, as well as light scattering. They observed that the morphology evolves from a percolating structure to clusters of a globular shape of a minority component around the time at which the PC transition is detected by light scattering.…”

Section: Alteration Of Time-evolution Of Phase Separationmentioning

confidence: 99%

Superstructure Formation in Thermoplastic Elastomer and Oil Systems. Formation of a Novel Microcellular Porous Structure

Mashita

Fukahori

2002

Polym J

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ABSTRACT:A novel microcellular porous structure, the product of a small proportion of a semi-crystalline thermoplastic elastomer (TPE) and a large proportion of low molecular weight oil, is examined. The structure is formed by the phase separation of a homogeneous mixture of TPE and oil. The system exhibits a unique three-dimensional continuous polymer network consisting of interconnected spherical cells of a few tens of micrometers in diameter. The detailed phase separation process is investigated utilizing optical microscopy, SEM, and DSC. A modulated structure, apparently attributable to spinodal decomposition, is observed in the initial stage of phase separation. However, during its evolution, this structure evolves into a clear network structure of a polymer-rich phase and clusters of a spherical oil-rich phase. Time evolution of D of a typical structure during the phase separation process at constant temperature is estimated to be D ∼ t 1 in the initial stage and D ∼ t 1/3 in the late stage. The character and role of differences in M w of components in the phase separation of the TPE/oil system are discussed in relation to the results of other studies.KEY WORDS Phase Separation / Percolation-to-Cluster Transition / Network Structure / Polymer Solution / Thermoplastic Elastomer / The phase separation process and morphology of polymer blend systems and alloys are both attractive and important from scientific and industrial perspectives, in part because the physical and mechanical properties of such polymer systems are highly dependent on their higher-order structures. Many types of phasecontrolled polymers have been developed and put to practical use over past decades.Despite numerous theoretical approaches, 1-4 most efforts to verify experimentally the kinetics of phase separation and its progress have generally been performed by indirect methods, such as time-resolved light scattering. [5][6][7][8][9] However, in the past five years, several studies have reported on direct observation of phase separation phenomena using laser scanning confocal microscopy, e.g., Ribbe, 10 Jinnai, 11, 12 and Hermansson. 13 Recently, the authors proposed new non-aqueous physical gels prepared with small proportions of semicrystalline thermoplastic elastomers (nearly 10 wt% polymer concentration) and large proportions of oils of low molecular weight. 14, 15 Observed directly with an optical microscope, the systems consist of threedimensional continuous polymer networks, constituted spherical cells of a few tens of micrometers in diameter. Each cell is connected to several other cells. Small openings occur at the connections between the cells: tunnels formed in the walls of the cells. This observation suggests that the oil-rich phases enclosed within the polymer cells are interconnected through the holes, and that the oil-rich phase is also continuous. We call this a "microcellular porous structure." The systems are quite stable thermally and dynamically and are currently used in industrial products as very soft nonaqueous and ...

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The percolation-to-cluster transition during spinodal decomposition of an off-critical polymer mixture. Observation by light scattering and optical microscopy

Abstract: Direct observation of the percolation-to-cluster transition of an off-critical mixture of polybutadiene and polyisoprene was achieved by optical microscopy. According to optical evidence, the transition occurs in a slow and a fast step not revealed in parallel light scattering experiments.

Cited by 42 publications

References 5 publications

Nanoporous Gold—Testing Macro-scale Samples to Probe Small-scale Mechanical Behavior

Nanoporous Gold—Testing Macro-scale Samples to Probe Small-scale Mechanical Behavior

On the mechanism of pinning in phase-separating polymer blends

Superstructure Formation in Thermoplastic Elastomer and Oil Systems. Formation of a Novel Microcellular Porous Structure

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