Morphological Behavior of Polystyrene<i>‐block‐</i>Polylactide/Polystyrene<i>‐block‐</i>Poly(ethylene oxide) Blends

Mao, Huiming

doi:10.1002/macp.200800087

Cited by 27 publications

(21 citation statements)

References 53 publications

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“…A rich phase behavior with interesting bulk morphologies was already reported by previous studies 25 26 27 28 29 30 31 . The governing parameters such as blend composition, volume fraction and molecular weight of each polymer component, and the Flory-Huggins segmental interaction parameter (χ) have also been extensively studied 25 27 29 . However, the frequent occurrence of macroscopic phase-separation between two di-BCPs often makes it difficult to achieve new and morphologically uniform nanostructures.…”

supporting

confidence: 72%

“…However, the frequent occurrence of macroscopic phase-separation between two di-BCPs often makes it difficult to achieve new and morphologically uniform nanostructures. One general criterion based on the minimization of interfacial energy to ensure uniform microphase separation in blends of A-B and A-C BCPs is that the χ between the B and C (χ BC ) blocks must be smaller than that between A and B (χ AB ) and between A and C (χ AC ), respectively 25 26 29 . In addition to considerations related to χ, the other key parameters mentioned above also need to be precisely optimized in order to prevent macrophase-separation between constituent BCPs.…”

mentioning

confidence: 99%

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Host-Guest Self-assembly in Block Copolymer Blends

Park

Kim

Jeong

et al. 2013

Sci Rep

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Ultrafine, uniform nanostructures with excellent functionalities can be formed by self-assembly of block copolymer (BCP) thin films. However, extension of their geometric variability is not straightforward due to their limited thin film morphologies. Here, we report that unusual and spontaneous positioning between host and guest BCP microdomains, even in the absence of H-bond linkages, can create hybridized morphologies that cannot be formed from a neat BCP. Our self-consistent field theory (SCFT) simulation results theoretically support that the precise registration of a spherical BCP microdomain (guest, B-b-C) at the center of a perforated lamellar BCP nanostructure (host, A-b-B) can energetically stabilize the blended morphology. As an exemplary application of the hybrid nanotemplate, a nanoring-type Ge2Sb2Te5 (GST) phase-change memory device with an extremely low switching current is demonstrated. These results suggest the possibility of a new pathway to construct more diverse and complex nanostructures using controlled blending of various BCPs.

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supporting

confidence: 72%

mentioning

confidence: 99%

Host-Guest Self-assembly in Block Copolymer Blends

Park

Kim

Jeong

et al. 2013

Sci Rep

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“…We proposed that the formation of the defective crystalline domains arose from a local demixing between a fraction of PEO and PLLA chains under the influences of restricted chain mobility of PLLA and the junction point constraint, thus generating the tiny PLLA crystallites intervened by the PEO block chains. As the blends of PEO and PLLA homopolymers with relatively low molecular weight were miscible in the melt, 15–19 the formation of composite microdomains by the PEO and PLLA blocks from their respective copolymers was expected, as that observed in the studies on PS‐ b ‐PEO/polystyrene‐ block ‐poly( d , l ‐lactide) binary blends reported by Mao and Hillmyer 20–22 and in our previous study 14 . A recent study by Chen et al further focused on the binary copolymer blends comprising PS‐ b ‐PEO and polystyrene‐ block ‐poly(acrylic acid) (PS‐ b ‐PAA), in which the hydrogen bonding between PEO and PAA blocks improved their miscibility to form the common microdomains and microphase‐separated against the domains composed of PS blocks; however, the crystallizable chain length of PEO was reduced by the hydrogen bonds, causing the crystallization to occur within a more confined region 23 …”

Section: Introductionsupporting

confidence: 62%

Confined crystallization in the binary blends of diblock copolymers bearing stereoisomeric isotactic and syndiotactic polypropylene

Chu

Chen

et al. 2021

Polymer Crystallization

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The morphology and crystallization behavior of the binary blends of two crystallineamorphous diblock copolymers bearing stereoisomeric crystalline blocks have been investigated. A polystyrene-block-isotactic polypropylene (S-iPP) and a polystyreneblock-syndiotactic polypropylene (S-sPP) were used to prepare a series of blends forming lamellar morphology. In the melt state, the PS blocks from these two diblock copolymers mixed intimately in the PS lamellar microdomains; meanwhile, the iPP and sPP blocks were found to form a miscible mixture in the PP domains. Under the effects of nanoscale confinement and the constraint imposed by the junction points, the iPP and sPP blocks exhibited the crystallization behavior greatly deviated from that in the neat diblock copolymers. A local demixing between a fraction of iPP and sPP chains was found to occur in the S-sPP-rich blend at low crystallization temperatures, which yielded the defective crystalline domains composed of alternately intervened iPP and sPP crystallites. This crystalline species displayed a significant depression of melting point located at the temperature around 10 C higher than the corresponding T c due to an excess surface free energy at the interface between the alternately intervened iPP and sPP crystallites.

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“…In contrast to (SI/IS)O materials where every χ ij >> 0, the LSO polymers studied herein feature low χ AC between the end blocks (χ LO K 0). Actual literature estimates for χ LO range from 0.0038 to −0.161 depending on end groups and measurement techniques (49,50). Combining any −0.161 < χ LO < 0.0038 with the aforementioned literature values χ LS = 0.080 and χ SO = 0.049 yields a frustrated system.…”

Section: Resultsmentioning

confidence: 97%

Manipulating the ABCs of self-assembly via low-χ block polymer design

Chang

Bates

Lee

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Block polymer self-assembly typically translates molecular chain connectivity into mesoscale structure by exploiting incompatible blocks with large interaction parameters (χ ij ). In this article, we demonstrate that the converse approach, encoding low-χ interactions in ABC bottlebrush triblock terpolymers (χ AC ≲ 0), promotes organization into a unique mixed-domain lamellar morphology, which we designate LAM P . Transmission electron microscopy indicates that LAM P exhibits ACBC domain connectivity, in contrast to conventional three-domain lamellae (LAM 3 ) with ABCB periods. Complementary small-angle X-ray scattering experiments reveal a strongly decreasing domain spacing with increasing total molar mass. Self-consistent field theory reinforces these observations and predicts that LAM P is thermodynamically stable below a critical χ AC , above which LAM 3 emerges. Both experiments and theory expose close analogies to ABA′ triblock copolymer phase behavior, collectively suggesting that low-χ interactions between chemically similar or distinct blocks intimately influence self-assembly. These conclusions provide fresh opportunities for block polymer design with potential consequences spanning all self-assembling soft materials.block polymer | self-assembly | polymer nanostructure | domain spacing | LAM P B lock polymers are a diverse class of soft materials capable of self-assembling into complex periodic nanostructures. Synthetic command over composition, dispersity, sequence, and molecular architecture enables control over the mesoscopic order and macroscopic thermal, mechanical, rheological, and transport properties (1-4). The phase behavior of "simple" linear AB diblock copolymers is universally parameterized by the segregation strength χ AB N and relative volume fraction f, where χ AB represents the effective Flory-Huggins binary interaction parameter and N is the total volume-averaged degree of polymerization. Mixing behavior, captured through the mean-field concept of χ AB , is central to block polymer self-assembly: the competing demands of minimizing interfacial energy and maximizing configurational entropy only favor microphase separation when A-B interactions are repulsive (χ AB > 0) (5, 6). Extension to higher-order multiblock polymers introduces additional interaction parameters (χ ij ) that impact self-assembly and properties (7). For example, introducing a mutually incompatible C block (χ AC > 0, χ BC > 0) generates a host of new morphologies dictated by the chain connectivity (ABC, ACB, or BAC) and intrinsic χ ij -values (8, 9). In this rich phase space, designing multiblock polymers with a combination of miscible and immiscible blocks can also access new structures and impart useful functions (10, 11). Perhaps the best-known examples of such systems are linear ABA′ triblock copolymers (χ AB > 0, χ AA′ ≈ 0): their high-value industrial applications as thermoplastic elastomers are entirely enabled by A/A′ mixing and chain connectivity, which together create physically cross-linked materials with ex...

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Morphological Behavior of Polystyrene‐block‐Polylactide/Polystyrene‐block‐Poly(ethylene oxide) Blends

Cited by 27 publications

References 53 publications

Host-Guest Self-assembly in Block Copolymer Blends

Host-Guest Self-assembly in Block Copolymer Blends

Confined crystallization in the binary blends of diblock copolymers bearing stereoisomeric isotactic and syndiotactic polypropylene

Manipulating the ABCs of self-assembly via low-χ block polymer design

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