Polyisoprene-Polystyrene Diblock Copolymer Phase Diagram near the Order-Disorder Transition

Khandpur, Ashish K.; Förster, Stephan; Bates, Frank; Hamley, Ian W.; Ryan, Anthony J.; Bras, Wim; Almdal, Kristoffer; Mortensen, K.

doi:10.1021/ma00130a012

Cited by 1,003 publications

(1,160 citation statements)

References 13 publications

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“…9 Here, we extend this concept to examine more closely the effect of varying the solvent selectivity. 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%

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: Discussionmentioning

confidence: 99%

Phase Behavior of a Block Copolymer in Solvents of Varying Selectivity

2000

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“…For example, for polystyrene/polyisoprene, χ SI is of order 0.1. 12 An abundance of the available coarse-grained statistical theories describing heterogeneous polymer thermodynamics employ χ as the thermodynamic force that drives microphase separation. 10 These theories can be further divided into three categories: (i) the strong segregation limit (SSL, χN ≫ 100), (ii) the weak segregation limit (WSL, χN ≤ 10), with (iii) the intermediate segregation regime spanning the two extremes.…”

Section: ■ Introductionmentioning

confidence: 99%

Thermodynamics of Symmetric Diblock Copolymers Containing Poly(styrene-ran-styrenesulfonic acid)

2012

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We examine the thermodynamic behavior of diblock copolymers representing the binary pairs of the ternary system: poly(dimethylsiloxane)/poly(ethylene-stat-propylene)/poly(styrene-ran-styrenesulfonic acid), D/EP/SS. We employ small-angle X-ray scattering, electron microscopy, and rheology to characterize the order-to-disorder transition temperature TODTand lamellar period d of 28 materials with varying molecular weights and sulfonation extents. These data are then interpreted in the context of self-consistent mean-field theory employing the continuous Gaussian chain model to deduce the interaction parameters as a function of temperature and sulfonation extent. We find that while EPD and SSEP are amenable to such treatment, the SS/D interaction forces SSD chains to stretch beyond the realm of applicability of the Gaussian chain model. Disciplines Polymer Science CommentsReprinted with permission from Macromolecules 46 (2013) ABSTRACT: We examine the thermodynamic behavior of diblock copolymers representing the binary pairs of the ternary system: poly(dimethylsiloxane)/poly(ethylene-stat-propylene)/ poly(styrene-ran-styrenesulfonic acid), D/E P /S S . We employ small-angle X-ray scattering, electron microscopy, and rheology to characterize the order-to-disorder transition temperature T ODT and lamellar period d of 28 materials with varying molecular weights and sulfonation extents. These data are then interpreted in the context of self-consistent mean-field theory employing the continuous Gaussian chain model to deduce the interaction parameters as a function of temperature and sulfonation extent. We find that while E P D and S S E P are amenable to such treatment, the S S /D interaction forces S S D chains to stretch beyond the realm of applicability of the Gaussian chain model.

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“…Most work [1] has focused on diblock copolymers AnBm. The chemical dissimilarity between the A and B species (quantified through the segmentsegment Flory-Huggins interaction parameter, X) produces periodic mesoscale morphologies [2][3][4] with symmetries determined by the overall volume fraction, f, of the A block and by the degree of immiscibility, XN, (where N=n+m is the total number of segments) . The lowest degree of immiscibility (xN ; :z 10.5) leading to mesoscale morphologies occurs for symmetric systems (f 0.5 or nz m) where a lamellar structure emerges .…”

Section: Introductionmentioning

confidence: 99%

“…The lowest degree of immiscibility (xN ; :z 10.5) leading to mesoscale morphologies occurs for symmetric systems (f 0.5 or nz m) where a lamellar structure emerges . Other equilibrium structures [2] established to date include spheres of A (B) arranged on a body-centered cubic lattice in a B (A) matrix, cylinders of A (B) arranged on a hexagonal lattice in a B (A) matrix, and bicontinuous gyroid channels .…”

Section: Introductionmentioning

confidence: 99%

Bridging Properties of Multiblock Copolymers

et al. 2002

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MaterialsLo s A la mos Nati on a l La boratory, an aff irmative action/equal opportunity e mploye r, is opera ted by the U niversit y o f Ca lifo rnia fo r t he U. S . Depa rtme nt o f Energ y u nde r co ntra ct W-7405 -ENG -3 6. By acceptance of this articl e, th e p ublishe r reco gnize s th at the U. S . Gove r nme nt re ta ins a n o nexclusive, royalty -f ree lice nse to pu blis h or rep ro duce the published form of this cont ribution , o r to a ll ow others to do so, for U .S . Gove rnme nt p urpos es. Los A lamo s Na tion al La bo rato ry req u est s that t h e publis he r ide ntify t his article as work performed unde r th e a us pic es of th e U . S. Depa rtme nt o f E ne r g y. Los A lamos N ational Labo ra tory strongl y sup ports a cade mic freedo m an d a researche r's rig ht to p u b lish ; as an institution, however, the Labo rato ry does not endo rse the viewpoint of a publicat i on o r gu ara nte e its t ec h nica l c o rrectness .For m 836 (8/00) ABSTRACTUsing self-consistent field theory, we attempt to elucidate the links between microscopically determined properties, such as the bridging fraction of chains, and mechanical properties of multiblock copolymer materials . We determine morphological aspects such as period and interfacial width and calculate the bridging fractions, and compare with experimental data .

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Polyisoprene-Polystyrene Diblock Copolymer Phase Diagram near the Order-Disorder Transition

Cited by 1,003 publications

References 13 publications

Phase Behavior of a Block Copolymer in Solvents of Varying Selectivity

Phase Behavior of a Block Copolymer in Solvents of Varying Selectivity

Thermodynamics of Symmetric Diblock Copolymers Containing Poly(styrene-ran-styrenesulfonic acid)

Bridging Properties of Multiblock Copolymers

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