Complex Phase Behavior of a Disordered “Random” Diblock Copolymer in the Presence of a Parent Homopolymer

Laurer, Jonathan H.; Ashraf, Arman; Smith, Steven D.; Spontak, Richard J.

doi:10.1021/la960807y

Cited by 15 publications

(22 citation statements)

References 34 publications

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“…Later, a complex morphology, Gyroid, has been extensively studied using TEMT. 35,37 Complicated 3D ''maze'' was beautifully imaged (see, for example, Figure 1 in ref 37), from which some structural features, e.g. volumetric fraction of one of the constituents, interfacial curvatures, 55,56 topology, 60 connectivity of domains 57,58 etc.…”

Section: D Morphological Studies Of Block Copolymersmentioning

confidence: 99%

Three-Dimensional Imaging in Polymer Science: Its Application to Block Copolymer Morphologies and Rubber Composites

Dohi¹,

Kimura²,

Kotani³

et al. 2007

Polym J

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ABSTRACT:New methods to visualize polymer morphologies in three-dimension (3D) in polymer science are reviewed. Here we concentrate on one of such 3D imaging technique, transmission electron microtomography (TEMT), and introduce some experimental studies using this novel technique. They are block copolymer morphologies during order-order transition between the two different morphologies and block copolymer thin film morphology also during morphological change due to confinement. Direct visualization of 3D structure of silica particle/rubber composite and related morphological analyses are shown. Subsequently, as a very hot topic of the 3D imaging, we show for the first time to characterize the morphological change in a silica particle/rubber composite upon stretching. It was found that the aggregates of silica particles were broken down upon stretching and many voids were generated near and between the silica particles. Local stress upon stretching inside the composite was inferred from the image intensity of the 3D reconstructed image. The local stress was found not only near the silica particles but also near the top of the voids. The observations indicated that the local stress increases the modulus, causing voids to form along the stretching direction. The thickness of the specimen after the stretching was also estimated from the 3D volume data, which turned out to be non-uniform and thinner than what is expected from the affine deformation. These experimental findings indicate that the rubber composite does not obey the assumption of the affine deformation at the nano-scale. Polymer materials are ubiquitous in our daily life. Such materials often consist of more than one species of polymers and thus become multi-component systems, such as in polymer blends, 1,2 block copolymers, 3 and fillers/polymer composites. 4 The multi-component systems often show phase-separated structures due to immiscibility of constituents. Studies to characterize such morphologies inside the materials have been growing intensively over the past few decades. Academic interest in complex fluids (to which polymeric systems belong) as well as the ceaseless industrial need for developing new materials motivates such studies.In academia, pattern formation and self-assembling processes of multi-component polymer systems are one of the most fascinating research themes in nonlinear, non-equilibrium phenomena.1 Likewise, nanometer-scale periodic structures formed in block copolymers in their equilibrium state are interesting because their self-assembly is driven by the subtle balance between the entropic block chain conformation and enthalpic interaction between the constituents. 3In industry, phase-separated polymer systems provide an important route to achieve superior physical properties. Hence, the structure-property relationship in multi-component polymeric materials is of significant importance, basic studies on which eventually render new designs of polymer materials satisfying the diverse requirements of industry.Filler/polymer comp...

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Section: D Morphological Studies Of Block Copolymersmentioning

confidence: 99%

Three-Dimensional Imaging in Polymer Science: Its Application to Block Copolymer Morphologies and Rubber Composites

Dohi¹,

Kimura²,

Kotani³

et al. 2007

Polym J

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“…Several previous studies have examined bicomponent block copolymers wherein one or more of the blocks is a random copolymer, excluding copolymers wherein a block is partially functionalized post‐synthesis. We refer to the specific case of such diblock copolymers as block random copolymers (BRCs).…”

Section: Introductionmentioning

confidence: 99%

Bicomponent Block Copolymers Derived from One or More Random Copolymers as an Alternative Route to Controllable Phase Behavior

Ashraf

Ryan

Satkowski

et al. 2017

Macromol. Rapid Commun.

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Block copolymers have been extensively studied due to their ability to spontaneously self-organize into a wide variety of morphologies that are valuable in energy-, medical-, and conservation-related (nano)technologies. While the phase behavior of bicomponent diblock and triblock copolymers is conventionally governed by temperature and individual block masses, it is demonstrated here that their phase behavior can alternatively be controlled through the use of blocks with random monomer sequencing. Block random copolymers (BRCs), i.e., diblock copolymers wherein one or both blocks are a random copolymer comprised of A and B repeat units, have been synthesized, and their phase behavior, expressed in terms of the order-disorder transition (ODT), has been investigated. The results establish that, depending on the block composition contrast and molecular weight, BRCs can microphase-separate. We also report that large variation in incompatibility can be generated at relatively constant molecular weight and temperature with these new soft materials. This sequence-controlled synthetic strategy is extended to thermoplastic elastomeric triblock copolymers differing in chemistry and possessing a random-copolymer midblock.

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“…Three-dimensional visualization of bicontinuous morphologies in block copolymer systems has been achieved [13][14][15] by transmission electron microtomography (TEMT). In this technique, TEM images are collected from a single specimen at incremental tilt angles over the maximum tilt-angle range permissible [16].…”

mentioning

confidence: 99%

Direct Measurement of Interfacial Curvature Distributions in a Bicontinuous Block Copolymer Morphology

et al. 2000

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Self-consistent field theory predicts that the complex phase behavior of block copolymers does not originate solely from the interface seeking constant mean curvature as once thought, but instead reflects competing minimization of interfacial tension and packing frustration. To test this prediction, we directly measure interfacial curvature distributions from a 3D image reconstruction of the bicontinuous gyroid morphology. Results obtained here reveal that the gyroid interface is not constant mean curvature and confirm the importance of packing frustration in the stabilization of such complex nanostructures. PACS numbers: 68.35.Ct, 42.30.Wb, 47.20.Hw, 83.70.Hq Block copolymers exhibit periodic nanostructures due to immiscibility between the dissimilar (A and B) sequences [1]. Classical block copolymer nanostructures include spheres of A(B) on a body-centered cubic lattice in a B(A) matrix, cylinders of A(B) on a hexagonal lattice in a B(A) matrix, and coalternating lamellae. Of considerable recent interest are several complex (bicontinuous) nanostructures-the perforated lamellar (PL), gyroid (G), and double-diamond (D) morphologies [2][3][4][5][6][7]. These nanostructures may develop if the copolymer composition ( f) falls within a narrow range between the cylindrical and lamellar morphologies, and can be difficult to distinguish experimentally. Block copolymer nanostructures once believed [2] to be D, exemplified by a Schwarz D surface with Pn3m symmetry, have been reclassified [8] on the basis of their small-angle X-ray scattering (SAXS) signatures as G, which is represented by the Schoen G surface with Ia3d symmetry. Identification of complex nanostructures by transmission electron microscopy (TEM) is often inconclusive, since they appear identical along several projection axes.Complex nanostructures also develop in surfactant and lipid systems due to the formation of surfaces with constant mean curvature (CMC) that minimize contact between immiscible moieties [9]. Since block copolymer nanostructures share common topological features with those of other self-organized systems, the concept of CMC minimal surfaces has been used [3] to explain the stability of complex block copolymer nanostructures. On the basis of self-consistent field theory (SCFT), Matsen and Bates [10,11] have recently proposed that the area-averaged mean curvature ͑͗H͒͘ governs the gross morphology (lamellar, bicontinuous, cylindrical, or spherical), whereas the standard deviation of the mean curvature distribution (s H ) determines the delicate stability of the complex nanostructures (G, D, or PL). This additional consideration results from packing frustration [12] and implies that, while a surface strives toward CMC, the mean curvature cannot be constant everywhere along the interface since the microdomain-forming blocks must uniformly fill space in the most entropically favored manner. Thus far, neither ͗H͘ nor s H has been measured experimentally despite their apparent importance.Three-dimensional visualization of bicontinuous morpho...

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Complex Phase Behavior of a Disordered “Random” Diblock Copolymer in the Presence of a Parent Homopolymer

Cited by 15 publications

References 34 publications

Three-Dimensional Imaging in Polymer Science: Its Application to Block Copolymer Morphologies and Rubber Composites

Three-Dimensional Imaging in Polymer Science: Its Application to Block Copolymer Morphologies and Rubber Composites

Bicomponent Block Copolymers Derived from One or More Random Copolymers as an Alternative Route to Controllable Phase Behavior

Direct Measurement of Interfacial Curvature Distributions in a Bicontinuous Block Copolymer Morphology

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