Quantifying the “Neutrality” of Good Solvents for Block Copolymers:  Poly(styrene-<i>b</i>-isoprene) in Toluene, Benzene, and THF

Huang, Cheng Fang; Chapman, Bryan; Lodge, Timothy; Balsara, Nitash P.

doi:10.1021/ma981259t

Cited by 39 publications

(68 citation statements)

References 19 publications

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“…In contrast to DBP and DEP, n-tetradecane (C14) is an isoprene-selective solvent. Accordingly, the phase diagram of SI (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) in C14, shown in Figure 1, is markedly different. Compared to the six normal and inverted ordered equilibrium structures observed in DBP and DEP, only three normal structures occur in C14.…”

Section: Resultsmentioning

confidence: 96%

“…We first present the phase diagrams of SI (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) in each of the solvents and then discuss the structural characterization of the various phases for each case. In the ensuing Discussion section, we interpret the general features of the phase diagrams in terms of established block copolymer solution principles.…”

Section: Resultsmentioning

confidence: 99%

“…Decreasing the alkyl chain length of dialkyl phthalates increases the selectivity toward styrene, and therefore DEP should be more styrene-selective than DBP. The phase diagram of SI- (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) in DEP is presented in Figure 1. Qualitatively, the results are similar to SI(11-21) in DBP, but there are several significant differences.…”

Section: Resultsmentioning

confidence: 99%

“…This suggests using the well-established principles that govern the melt phase behavior of diblock copolymers as a basis for understanding their solutions. Previously, we invoked the qualitative notion of trajectories across the SI melt phase map upon varying φ or T to describe the phase behavior in concentrated solutions of SI (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) in DOP and DBP. 9 Here, we extend this concept to examine more closely the effect of varying the solvent selectivity.…”

Section: Discussionmentioning

confidence: 99%

“…This is illustrated in Figure 11, where six trajectories associated with the expected phase behavior in each of the investigated solvents are superimposed onto the melt phase map, presented in terms of an effective PS volume fraction (f ′ PS ) and degree of segregation eff N. The melt phase map is drawn based on extensive results for SI melts, 45,46 with the polystyrene composition as the independent variable, a PS reference volume for N, and eff from eq 2. As a common reference, the trajectories originate at the estimated segregation of neat SI (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) at 0°C.…”

Section: Discussionmentioning

confidence: 99%

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Phase Behavior of a Block Copolymer in Solvents of Varying Selectivity

2000

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The effect of the thermodynamic selectivity of a solvent on the self-assembly of a styreneisoprene (SI) diblock copolymer with block molecular weights of 1.1 × 10 4 and 2.1 × 10 4 g/mol is investigated. We explore the phase behavior from the melt state to dilute solution in solvents that are of varying selectivities for the two blocks. Bis(2-ethylhexyl) phthalate (DOP) is a neutral good solvent for SI. Di-n-butyl phthalate (DBP) and diethyl phthalate (DEP) are good solvents for PS but marginal and poor, respectively, for PI. Tetradecane (C14) is utilized as a complementary solvent that is good for PI but poor for PS. Small-angle X-ray scattering (SAXS) and static birefringence are used to locate and identify order-order (OOT) and order-disorder transitions (ODT). Dynamic and static light scattering were used to characterize the dilute solution micellar behavior. The neat polymer forms the gyroid (G 1) morphology at low temperature, an OOT to hexagonal-packed cylinders (C1) occurs at 185°C, and the ODT is located at 238°C. Dilution with DOP decreases the OOT temperature in agreement with the dilution approximation, i.e., OOT ∼ φ -1 , but the ODT follows a stronger dependence of ODT ∼ φ -1.4 . The slightly selective solvent DBP stabilizes the ordered state relative to DOP. Rich lyotropic and thermotropic behavior is observed among regions of lamellae (L), inverted gyroid (G2), inverted hexagonal-packed cylinders (C2), and inverted body-centered-cubic spheres (S2 bcc ). Solutions in DEP display similar morphological behavior, along with significantly increased ODT temperatures. Because of the asymmetric block copolymer composition, the phase behavior in the isoprene-selective solvent C14 is markedly different, as only G1, C1, and S1 bcc phases are observed. The overall sequence of phases with dilution and/or heating is rationalized on the basis of diagonal trajectories across the phase map (temperature vs composition) for undiluted block copolymers: addition of a neutral solvent corresponds to increasing the temperature and thus a "vertical" trajectory, whereas the partitioning between microdomains of a selective solvent amounts to a "horizontal" trajectory to a renormalized block volume composition. However, a variety of novel features are observed in DEP: the formation of face-centered-cubic packed micelles, a reentrant thermotropic ODT, and a large window of L + C 2 coexistence. The dependence of the principal length scale, d*, on φ, T, and structure is also considered. The strongly temperature-dependent selectivity produces a crossover in the scaling of d* vs φ for the lamellar phase: the addition of a selective solvent increases d*, but as the solvent becomes neutral, d* decreases. This phenomenon is captured by selfconsistent mean-field calculations.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Phase Behavior of a Block Copolymer in Solvents of Varying Selectivity

2000

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Concentrated Solutions

2005

Block Copolymers in Solution: Fundamentals and Applications

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Controlling Ordered Structures of PS‐b‐P2VP Block Copolymer Thin Film by Tuning Solvent Evaporation Rate

Shamsudin

Takenaka

Hasegawa

2017

Macromolecular Symposia

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Summary Selective solvents for each block were chosen to induce specific blocks of the Polystyrene‐block‐poly(2vinylpyridine) (PS‐b‐P2VP) block copolymer (BCP) thin film with the purpose of comparing the degree of block swelling affected by solvent vapors onto the thin film. Solvents with high boiling point have been preferred for this study, because these solvents evaporate slowly, and allowing the block copolymer to self‐assemble properly. Toluene and acetic acid were considered as suitable solvents for polystyrene (PS) and poly(2vinylpyridine) (P2VP), respectively. We prepared 1 wt% PS‐b‐P2VP BCP (79.0k‐b‐36.5k kg/mol) solution in a mixed solvent of toluene and tetrahydrofuran (THF) with a ratio of 7:3. Then, applied solvent annealing to the thin films with toluene and acetic acid at 21 °C for 3 hours, 6 hours and 9 hours. Thermal annealing to the thin films at 80 °C, 100 °C, 150°C, 200 °C and 250 °C for 24 hours was also applied. The morphology of the resulting thin film has been characterized using the atomic force microscopy (AFM). The formation of the block copolymer structure on thin film revealed highly affected by the evaporation rate owing to the decreased polymer mobility occurred by lower temperature of the solvent with high boiling point.

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Quantifying the “Neutrality” of Good Solvents for Block Copolymers: Poly(styrene-b-isoprene) in Toluene, Benzene, and THF

Cited by 39 publications

References 19 publications

Phase Behavior of a Block Copolymer in Solvents of Varying Selectivity

Phase Behavior of a Block Copolymer in Solvents of Varying Selectivity

Concentrated Solutions

Controlling Ordered Structures of PS‐b‐P2VP Block Copolymer Thin Film by Tuning Solvent Evaporation Rate

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