Micro-<i>vs.</i>macro-phase separation in binary blends of poly(styrene)-poly(isoprene) and poly(isoprene)-poly(ethylene oxide) diblock copolymers

Frielinghaus, Henrich; Hermsdorf, N.; Almdal, Kristoffer; Mortensen, K.; Messe, Loic; Corvazier, L.; Fairclough, J. Patrick A.; Ryan, Anthony J.; Olmsted, Peter D.; Hamley, Ian W.

doi:10.1209/epl/i2001-00205-7

Cited by 51 publications

(63 citation statements)

References 16 publications

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“…Both the relative and absolute magnitudes of each χ ij , convolved with the molecular sequence, underpin the self-assembly of multiblock polymers. For example, given I, S, and O blocks with χ IO > χ IS ≈ χ SO (47,48), SIO connectivity imposes costly high-χ interactions between adjacent blocks (χ BC > χ AB ≈ χ AC ), whereas ISO connectivity alleviates this penalty by not inherently requiring I/O (A/C) interfaces. ISO and SIO phase diagrams are consequently distinct due to so-called frustration.…”

Section: Resultsmentioning

confidence: 99%

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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Section: Resultsmentioning

confidence: 99%

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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“…72 The monomer reference volume for these calculations is 118 Å 3 and Flory-Huggins interaction parameters ͑͒, statistical segment lengths ͑b͒, and degrees of polymerization ͑N͒ are all scaled to this quantity. The ͑here taken at 100°C͒ 80 72,77 SCFT calculations were performed on hypothetical sets of ISO triblocks that mimic those prepared experimentally. N of each IS diblock is kept constant at our experimental values and the lengths of the PEO chains are varied.…”

Section: A Scft Methodologymentioning

confidence: 99%

Polydispersity effects in poly(isoprene-b-styrene-b-ethylene oxide) triblock terpolymers

Meuler

Ellison

Qin

et al. 2009

The Journal of Chemical Physics

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Four hydroxyl-terminated poly͑isoprene-b-styrene͒ diblock copolymers with comparable molecular weights and compositions ͑equivalent volume fractions of polyisoprene and polystyrene͒ but different polystyrene block polydispersity indices ͑M w / M n = 1.06, 1.16, 1.31, 1.44͒ were synthesized by anionic polymerization using either sec-butyllithium or the functional organolithium 3-triisopropylsilyloxy-1-propyllithium. Poly͑ethylene oxide͒ ͑PEO͒ blocks were grown from the end of each of these parent diblocks to yield four series of poly͑isoprene-b-styrene-b-ethylene oxide͒ ͑ISO͒ triblock terpolymers that were used to interrogate the effects of varying the polydispersity of the middle bridged polystyrene block. In addition to the neat triblock samples, 13 multicomponent blends were prepared at four different compositions from the ISO materials containing a polystyrene segment with M w / M n = 1.06; these blends were used to probe the effects of increasing the polydispersity of the terminal PEO block. The melt-phase behavior of all samples was characterized using small-angle X-ray scattering and dynamic mechanical spectroscopy. Numerous polydispersity-driven morphological transitions are reported, including transitions from lamellae to core-shell gyroid, from core-shell gyroid to hexagonally packed cylinders, and from network morphologies ͓either O 70 ͑the orthorhombic Fddd network͒ or core-shell gyroid͔ to lamellae. Domain periodicities and order-disorder transition temperatures also vary with block polydispersities. Self-consistent field theory calculations were performed to supplement the experimental investigations and help elucidate the molecular factors underlying the polydispersity effects. The consequences of varying the polydispersity of the terminal PEO block are comparable to the polydispersity effects previously reported in AB diblock copolymers. Namely, domain periodicities increase with increasing polydispersity and domain interfaces tend to curve toward polydisperse blocks. The changes in phase behavior that are associated with variations in the polydispersity of the middle bridged polystyrene block, however, are not analogous to those reported in AB diblock copolymers, as increases in this middle block polydispersity are not always accompanied by ͑i͒ increased domain periodicities and ͑ii͒ a tendency for domain interfaces to curve toward the polydisperse domain. These results highlight the utility of polydispersity as a tool to tune the phase behavior of ABC block terpolymers.

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“…In addition to AB/A′B′ blends, the behavior of AB/AC blends have been documented 9–21. While we are unaware of theoretical treatments of these blends, there are a few guiding principles.…”

Section: Introductionmentioning

confidence: 99%

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

Mao

2008

Macro Chemistry & Physics

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The morphological behavior of PS‐containing diblock copolymer blends is reported. Three sets of PS/PLA and PS/PEO blends are prepared and evaluated by SAXS, WAXS, DSC, and DMA. No macrophase separation is observed, and the formation of PLA/PEO composite cylinders is identified by SAXS for all compositions. The PLA and PEO segments in these blends have been found to be miscible and the crystallization of the confined PEO is suppressed in the ordered nanostructures. The domain spacing, diameter of composite cylinders, and order/disorder transition temperature could be tuned by varying the blend composition in the binary blends.magnified image

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Micro-vs.macro-phase separation in binary blends of poly(styrene)-poly(isoprene) and poly(isoprene)-poly(ethylene oxide) diblock copolymers

Cited by 51 publications

References 16 publications

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

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

Polydispersity effects in poly(isoprene-b-styrene-b-ethylene oxide) triblock terpolymers

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

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