Density Discontinuity at the Microphase Separation Transition of a Symmetric Diblock Copolymer

Kasten, H.; Stuehn, B.

doi:10.1021/ma00117a069

Cited by 34 publications

(36 citation statements)

References 2 publications

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“…ODT temperatures of 139 and 161 °C for BF6.0‐2.5 and BF1.8‐2.5, respectively, determined by DSC (Fig. 7),29 were consistent with the SAXS measurements. The relatively large heat of transition observed at the ODT for the polymers is consistent with the remarkably large χ values for these materials, as calculated later 30…”

Section: Resultssupporting

confidence: 84%

Synthesis and self‐assembly of highly incompatible polybutadiene–poly(hexafluoropropylene oxide) diblock copolymers

Zhu

Edmonds

Hillmyer

et al. 2005

J Polym Sci B Polym Phys

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A versatile coupling reaction for the preparation of polybutadiene–poly‐(hexafluoropropylene oxide) (BF) diblock copolymers is described. Six diblock copolymers with different block lengths were characterized by nuclear magnetic resonance spectroscopy and size exclusion chromatography; all six had total molecular weights below 15,000. Microphase separation of the block copolymers in the bulk state was established by small‐angle X‐ray scattering (SAXS) and differential scanning calorimetry. SAXS data suggest that the diblocks are characterized by an unusually large Flory‐Huggins interaction parameter, χ, on the order of 10. However, extraction of χ from the order–disorder transition gave large (order 1) but significantly different values, thereby suggesting that these copolymers are too small and too strongly interacting to be described by block copolymer mean‐field theory. Dynamic light scattering was used to analyze dilute solutions of the title block copolymers in four selective organic solvents; the sizes of the micelles formed were solvent dependent. The micellar aggregates were large and nonspherical, and this is also attributed to the high degree of incompatibility between the two immiscible blocks. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3685–3694, 2005

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Section: Resultssupporting

confidence: 84%

Synthesis and self‐assembly of highly incompatible polybutadiene–poly(hexafluoropropylene oxide) diblock copolymers

Zhu

Edmonds

Hillmyer

et al. 2005

J Polym Sci B Polym Phys

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“…A change in density of the systems is less likely to account for this behavior, since values for the volume discontinuities at the order-disorder transitions are much smaller, typically around 0.3%. 13 Altogether, this behavior resembles a melting of the long-range ordered arrays of microdomains. The scattering patterns recorded at temperatures well above this network disordering transition still indicate a well-pronounced structure factor maximum, which can be described using the Percus-Yevick hard sphere approximation for an assembly of short-range ordered spheres.…”

Section: Temperature-dependent Morphology Of Annealed Gelsmentioning

confidence: 87%

“…The very low transition enthalpies, between 10 Ϫ2 and 10 Ϫ1 J/g, are close to those values reported for endotherms detected at the order-disorder transitions of bulk-block copolymer systems. 13 The positions of these endotherms depend on the triblock copolymer content. Gels with a copolymer content of 15 and 20 wt % revealed endotherms around 105 and 120°C, respectively (see Figure 1).…”

Section: Dsc Experimentsmentioning

confidence: 99%

Long-range order in physical networks of gel-forming triblock copolymer solutions

Kleppinger

Mischenko

Reynaers

et al. 1999

J. Polym. Sci. B Polym. Phys.

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“…During the past few years the pressure dependence of phase transitions in polymer blends and block copolymers has been a subject of intense research both experimentally [1][2][3][4][5][6][7][8][9][10][11] and theoretically [12 -17]. It has been found that the upper critical solution transition (UCST) of polymer mixtures and the order-to-disorder transition (ODT) for block copolymers are only weakly dependent on pressure.…”

mentioning

confidence: 99%

Effect of Hydrostatic Pressure on Closed-Loop Phase Behavior of Block Copolymers

et al. 2003

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The effect of hydrostatic pressure (P) on closed-loop phase behavior of deuterated polystyrene-block-poly(n-pentyl methacrylate) copolymers [dPS-PnPMA] was investigated by using small-angle neutron scattering and birefringence. For P<20.7 bar, dPS-PnPMA exhibited a lower disorder-to-order transition temperature (T(LDOT)) at 175 degrees C, and then an upper order-to-disorder transition temperature (T(UODT)) at 255 degrees C. With increasing pressure both T(LDOT) and T(UODT) were markedly changed, where dT(LDOT)/dP was 725 degrees C/kbar and dT(UODT)/dP was -725 degrees C/kbar. These are consistent with predictions by the Clausius-Clapeyron equation using measured values of the volume and enthalpy changes of both transitions. The large pressure coefficients imply that the closed-loop phase behavior observed for PS-PnPMA is an entropic-driven phase transition.

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Density Discontinuity at the Microphase Separation Transition of a Symmetric Diblock Copolymer

Cited by 34 publications

References 2 publications

Synthesis and self‐assembly of highly incompatible polybutadiene–poly(hexafluoropropylene oxide) diblock copolymers

Synthesis and self‐assembly of highly incompatible polybutadiene–poly(hexafluoropropylene oxide) diblock copolymers

Long-range order in physical networks of gel-forming triblock copolymer solutions

Effect of Hydrostatic Pressure on Closed-Loop Phase Behavior of Block Copolymers

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