Notes

Cahn, R. S.; Druce, J. G. F.; Dorée, Charles; Petrow, Vladimir; Taylor, T. W. J.; Crawford, Charles E. J.; Robinson, Robert; Streight, H. R. L.; Menzies, R. C.; Walker, A.R.

doi:10.1039/jr9340001129

Cited by 6 publications

(5 citation statements)

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“…Experimentally, it is found p = 1 and a = 1 /3 for most polymeric blends in the intermediate stage; and p = 3 and a = 1 for a system in the late stage of spinodal decomposition with strong hydrodynamic contributions (37,38,48,(53)(54)(55). In this study, the accessible q-range (0.002 to 0.02 nm-') shows that the limiting power law exponent at late times for the time dependence of I(q,J varied from 3 for the pure blend (we, = 0) to 1 for the compatibilized blend with wB, = 0.086.…”

Section: Phase Separation Kineticsmentioning

confidence: 99%

Evolution of phase morphology in compatibilized polymer blends at constant quench depths: Complementary studies by light scattering and transmission electron microscopy

Jackson

Sung

Han

1997

Polymer Engineering & Sci

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The effect of added block copolymer on the phase separation and morphology evolution in a partially miscible blend of polystyrene and polybutadiene near the critical composition is studied by temperature jump light scattering (TJLS) and transmission electron microscopy (TEM). As block copolymer is added, the phase boundary is shifted to lower temperatures and the phase separation process is slowed dramatically. Since the quench depth greatly affects the rate of phase separation in any blend system, we have used equivalent quench depths by adjusting for the shift in the phase boundary as block copolymer is added. The morphology evolution of these ternary blends was studied by preparing TEM specimens at equivalent shallow quench depths (AT = 1 .SoC) and allowing each blend mixture to coarsen for the time required to reach a specific constant size, or q-value, using the TJLS data on the kinetics of phase separation. The q-range selected was q -0.003-0.005 nm-I, which corresponds to a spacing of 1-2 pm in real space. The combination of light scattering and microscopy techniques more rigorously describes the compatibilization process in these complex ternary systems.

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Section: Phase Separation Kineticsmentioning

confidence: 99%

Evolution of phase morphology in compatibilized polymer blends at constant quench depths: Complementary studies by light scattering and transmission electron microscopy

Jackson

Sung

Han

1997

Polymer Engineering & Sci

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“…Such phenomena occur because in a binary system usually one species is energetically attracted to the wall more than the other. In small-molecule systems, wetting phenomena often occur close to the bulk critical point onlydue to the critical vanishing of the interfacial tension between coexisting phases at T, one expects walls always to be wet near T,, while far away from T, the interfacial tension may be large in comparison to the surface energy gained by surface enrichment of the preferred species, and the surface is not wetted [6]. In contrast, for partially compatible polymer mixtures the interfacial tension is anomalously small [7-91: therefore "complete wetting" (Fig.…”

Section: Introduction and Overviewmentioning

confidence: 99%

Surface effects on polymer blends and block copolymer melts: Theoretical concepts of surface enrichment, surface induced phase separation and ordering

Binder

1995

Acta Polymerica

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Surfaces have a profound effect on the structure and related properties of multiphase polymeric materials, such as polymer mixtures and block copolymer mesophases. In particular, phase transitions in the bulk (unmixing, microphase separation, etc.) may be complemented by surface-induced transitions (formation of wetting layers, surface-directed spinodal decomposition, surface-induced ordering). This review gives a brief introduction to the phenomenological theories of such phenomena, emphasizing the simplest approach based on Flory-Huggins-de Gennes free energy functionals and associated Monte Carlo simulations. More sophisticated theories and recent experiments are mentioned briefly.concentration (e), there is a coexistence curve separating the one-phase region (above) from the two-phase region (below) in the bulk.This two-phase region ends at Teb in a bulk critical point (without loss of generality we assume an upper critical solution temperature (UCST) here).The difference dQ= &,& -&,& is the "order parameter"of the transition describing phase separation in the two coexisting phases (&izd,,, &J. The wetting transition is a singularity of the surface excess free energy associated with the wall and occurs at T, for a path along the coexistence curve. The corresponding order parameter profile may change from a nonwet state of the surface (surface excess order parameter e,, the integral of the shaded region, being finite) to a wet state in either a continuous fashion ("critical wetting") or via a discontinuous jump at T, ("first-order wetting"). The schematic "adsorption isotherms" in the lower part of the figure show the behavior as a function of a control parameterp approaching the coexistence curve from the one-phase region atp,,,, @=pressure for the fluid, orp=chemical potential difference d p for a mixture, etc.). When e,-one then has"comp1ete wetting"whi1e Q~@~~~~) <-(for T< T,) means "incomplete wetting". For T, < T < Cre a further discontinuity occurs at the "prewetting transition".Fax: +49-6 13 1-3 9-5 44 1

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“…xls E x~~ can moreover be verified directly by scattering methods. Condition (1) cannot be tested directly. Whether it is satisfied, can only be decided at the end of the miscibility analysis.…”

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confidence: 99%

Miscibility of poly (styrene‐co‐methylmethacrylate)s differing in composition

Kohl

Seifert

Hellmann

1990

J Polym Sci B Polym Phys

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SynopsisThe mutual miscibility of random poly( styrene-co-methylmethacry1ate)s with different compositions hut a constant molecular weight of M , 150,000 was studied at room temperature and at 180°C. Compatibility was analyzed with films cast from solutions with different solvents. The reliability of the analytical technique is discussed. The miscibility windows { x , y , } , which define the limits of miscibility of the blends of a given copolymer P(S,MMAI-,) with other copolymers P (S,MMA,,), were determined for all x. The widths I xy z I of these windows are, contrary to the predictions of the Flory-Huggins model, different for yx > x and yx < z, and depend strongly on x . Miscibility is better for blends with a high MMA content. The windows are markedly wider at room temperature. Many blends are, therefore, "semicompatible," i.e., have a critical point of the LCST type between room temperature and 180°C.

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Cited by 6 publications

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Evolution of phase morphology in compatibilized polymer blends at constant quench depths: Complementary studies by light scattering and transmission electron microscopy

Evolution of phase morphology in compatibilized polymer blends at constant quench depths: Complementary studies by light scattering and transmission electron microscopy

Surface effects on polymer blends and block copolymer melts: Theoretical concepts of surface enrichment, surface induced phase separation and ordering

Miscibility of poly (styrene‐co‐methylmethacrylate)s differing in composition

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