Microphase-Separation Behavior of Triblock Copolymer Melts. Comparison with Diblock Copolymer Melts

Shaomin,; Mingvanish, Withawat; Turner, Simon C.; Chaibundit, Chiraphon; Fairclough, J. Patrick A.; Heatley, Frank; Matsen, Mark W.; Ryan, Anthony J.; Booth, Colin

doi:10.1021/ma000154z

Cited by 89 publications

(100 citation statements)

References 34 publications

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“…16 Nevertheless, the phase behavior appears manageable for those architectures comprised of just two segment types. Among this class of architectures, the ABA triblock is the next most studied block copolymer, 17 mainly because of its commercial use as a thermoplastic elastomer. There were also a considerable number of early experiments on star block copolymers, formed by joining three or more diblocks together by their ends.…”

Section: ■ Introductionmentioning

confidence: 99%

Effect of Architecture on the Phase Behavior of AB-Type Block Copolymer Melts

2012

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Equilibrium phase diagrams are calculated for a selection of two-component block copolymer architectures using self-consistent field theory (SCFT). The topology of the phase diagrams is relatively unaffected by differences in architecture, but the phase boundaries shift significantly in composition. The shifts are consistent with the decomposition of architectures into constituent units as proposed by Gido and co-workers, but there are significant quantitative deviations from this principle in the intermediatesegregation regime. Although the complex phase windows continue to be dominated by the gyroid (G) phase, the regions of the newly discovered Fddd (O 70 ) phase become appreciable for certain architectures and the perforated-lamellar (PL) phase becomes stable when the complex phase windows shift toward high compositional asymmetry. ■ INTRODUCTIONThe phase behavior of AB diblock copolymer melts has been well studied experimentally, 1 and self-consistent field theory (SCFT) 2 has been remarkably successful in explaining the equilibrium phase behavior.3−5 Vavasour and Whitmore 6 produced the first SCFT phase diagram, but it was limited to the classical lamellar (L), cylindrical (C), and bcc spherical (S) phases. Matsen and Schick 7 then extended it to include complex phases, predicting the gyroid (G) phase to be more stable than the perforated-lamellar (PL) phase as confirmed later by experiment.8 In a subsequent calculation by Matsen and Bates, 9 a narrow closed-packed spherical (S cp ) phase was predicted along the order−disorder transition (ODT), which has since been associated with a region of densely packed spherical micelles. 10,11 Most recently, the Fddd (O 70 ) phase was predicted by Tyler and Morse 12 and later observed in experiment.13−15 Figure 1 shows the current up-to-date SCFT phase diagram for AB diblock copolymer melts.The AB diblock is just the simplest block copolymer among an unlimited variety of different architectures. It is natural to ask how the phase behavior changes for other architectures, but this has proven to be a daunting task as soon as a third chemically distinct component is involved; in fact, even the simple linear ABC triblock exhibits so many morphologies that we might never catalogue them all. 16 Nevertheless, the phase behavior appears manageable for those architectures comprised of just two segment types. Among this class of architectures, the ABA triblock is the next most studied block copolymer, 17 mainly because of its commercial use as a thermoplastic elastomer. There were also a considerable number of early experiments on star block copolymers, formed by joining three or more diblocks together by their ends. The general conclusion from these studies is that all AB-type architectures have similar phase diagrams, but with significantly shifted phase boundaries. The reason for the similarity is fairly well understood. Although mechanical properties are completely altered by snipping the middle B blocks of an ABA triblock melt in half, the free energy is re...

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Section: ■ Introductionmentioning

confidence: 99%

Effect of Architecture on the Phase Behavior of AB-Type Block Copolymer Melts

2012

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“…[3] As for diblock copolymers, fluctuations in the disordered melt were found to cause an increase in (vr v ) c , i. e. a decrease in the MST. In a recent report [8] we have argued that the fluctuation correction of Fredrickson and Helfand [9] holds equally well for diblock and triblock copolymers.…”

Section: Introductionmentioning

confidence: 92%

Microphase separation in oxyethylene/oxybutylene copolymers with diblock and triblock architectures

Chaibundit

Mingvanish

Turner

et al. 2000

Macromol. Rapid Commun.

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EBE and BEB triblock copolymers were prepared and characterized. Microphase separation in the melt state was studied, and the results combined with those for EB and BEB copolymers reported previously. The microphase separation temperature (MST) was determined from the temperature dependence of SAXS. There was a large difference in MST between the diblock and triblock copolymers as expected from theory. The Flory‐Huggins parameter (χ) was independent of block architecture for all three series provided that the E block lengths in the EBE copolymers exceeded 65.

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“…3 Moreover, theoretical analysis and experimental data show that the phase diagrams of A n/2 B m A n/2 and B m/2 A n B m/2 triblock copolymers are asymmetric. [2][3][4][5][6] The architecture also affects the solution properties of triblock copolymer. In the presence of selective solvent for the A block, coupling between different micelles may occur in B m/2 A n B m/2 triblock copolymer, but this does not happen in A n/2 B m A n/2 triblock copolymer.…”

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“…7,8 The structures of oxyethylene/oxybutylene diblock and triblock copolymers (represented by E m B n , B n/2 E m B n/2 and E m/2 B n E m/2 , where E is oxyethylene unit and B is oxybutylene unit) in the melt and in the solid state have been systematically compared in terms of the overall length of the block copolymer and the length of single E block. 2,4,9 It has been shown that B n/2 E m B n/2 and E m/2 B n E m/2 triblock copolymers have similar structure including long period and melting temperature, though their order-disorder transition temperatures are different. 2,4,9 However, in B n/2 E m -B n/2 triblock copolymer the central crystallizable E block is connected with amorphous B block at both ends of the E block, whereas in E m/2 B n E m/2 both ends of the amorphous B block are immobilized at the interface when crystallized from micro-phase separated state.…”

mentioning

confidence: 99%

“…2,4,9 It has been shown that B n/2 E m B n/2 and E m/2 B n E m/2 triblock copolymers have similar structure including long period and melting temperature, though their order-disorder transition temperatures are different. 2,4,9 However, in B n/2 E m -B n/2 triblock copolymer the central crystallizable E block is connected with amorphous B block at both ends of the E block, whereas in E m/2 B n E m/2 both ends of the amorphous B block are immobilized at the interface when crystallized from micro-phase separated state. Since both the B block and the E block change their conformation during crystallization, crystallization of the E block is inevitably affected by the amorphous B block.…”

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confidence: 99%

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