Phase Separation in Polymer Blends Near a Surface

Saout-Elhak, A.; Benhamou, M.; Daoud, M.

doi:10.1051/jp2:1997141

Cited by 7 publications

(13 citation statements)

References 12 publications

(15 reference statements)

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“…These complex systems then present weak microphase separations similar to that observed more clearly on polymer blends (28). And of course near a surface some specific segregation may occur (29). The magnetic resonance response of a multiphase polymer with microscopic FIG.…”

Section: Expected Phenomenasupporting

confidence: 54%

Molecular Conformation and Mobility of Polyamines Adsorbed on Silica Studied by Spin Labeling

Afif

Hommel

Legrand

et al. 1999

Journal of Colloid and Interface Science

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Section: Expected Phenomenasupporting

confidence: 54%

Molecular Conformation and Mobility of Polyamines Adsorbed on Silica Studied by Spin Labeling

Afif

Hommel

Legrand

et al. 1999

Journal of Colloid and Interface Science

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“…We note that we can use the same analysis as pointed out in reference [24], to show that the boundary condition (20) can naturally emerge from the model recently introduced by Cohen and Muthukumar [37], in the context of the critical wetting of twocomponent polymer blends. As shown previously [38], the surface fraction is an explicit function of the free energy necessary to adsorb one monomer at surface.…”

Section: The Model and Equation For The Profilementioning

confidence: 82%

“…Before the explicit determination of the equilibrium profile below the critical point T K , we first compare the bulk compositionx b to the surface compositionx 0 , as already done for binary mixtures [24]. Since one is close to the critical point, this comparison should be possible only if this surface composition is small enough.…”

Section: Profile Shape Below the Critical Pointmentioning

confidence: 99%

“…Since one is close to the critical point, this comparison should be possible only if this surface composition is small enough. Equating these two compositions implies the existence of some characteristic temperature termed compensation temperature [24], that we denote by T 1 . We find for the corresponding Flory interaction parameter, denoted by χ 1 , the value…”

Section: Profile Shape Below the Critical Pointmentioning

confidence: 99%

“…Finally, this work must be regarded as a natural extension of a previous one [24], which was concerned with the same problem, but in the absence of solvent. This paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

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Phase separation of polymer blends in solution near adsorbing surface

2000

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In this paper, we consider a mixture of two polymers A and B of different chemical nature, dissolved in a common good solvent, in contact with an interacting surface. We start from a mixture of two incompatible homopolymers A and B in the molten state, and assume that the surface adsorbs strongly one or both polymer species at high temperature. It is assumed that this is a strong adsorption, so that chains cannot desorb once they are linked to the surface. This constrains the system to a quenched composition on the surface. Once the adsorption process is finished, a quantity of a good solvent is added to get a semi-dilute solution. We assume that demixing transition in the presence of solvent occurs at lower temperature. The purpose is to discuss the influence of the quenched surface fluctuations on the critical properties of the mixture. Within the framework of the so-called blob model, we determine the exact shape of the composition profile as a function of the distance z to the surface, for any value of the relevant parameters, namely, the temperature T , the molecular weight M , the monomer concentration c and the surface composition x 0. Our analysis reveals a universal character of the composition profile for D z ξt, where the characteristic size D is some known length depending on the relevant parameters of the problem, and not on temperature, and ξt is the thermal correlation length. Near surface, for a z D (a is the monomer size), the profile is no longer universal, and in particular, it is sensitive to the boundary condition. Far from the surface, that is z ξt, the profile tends exponentially to its bulk value. We show that the length D approaches its lowest value as the surface composition reaches its saturated value l. In this limit, we find that the profile shape is a characteristic of critical adsorption in simple binary fluid mixtures. Finally, this work must be regarded as a natural extension of a previous one, which was concerned with the same problem, but in the absence of solvent.

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Increases in Miscibility of a Binary Polymer Blend Confined within a Nanoparticle Packing

et al. 2023

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Despite various physical and chemical strategies that have been explored, compatibilization of polymer blends has proved elusive. Confinement of polymers has shown to induce substantial and at times unexpected changes in glass-transition temperature, dynamics, and morphology of these materials. Although confinement of blends to thin films have shown to influence phase separation structure and chain mobility, the impact of confinement on the miscibility of polymer mixtures is much less understood. Here, we present a computational study using field-theoretic simulations to understand the thermodynamics of polymer blends that are confined in the interstices of nanoparticle packings where both polymers have neutral interactions with the nanoparticle surfaces. We calculate their binodal phase envelopes and show that two polymers that would undergo macroscopic phase separation become miscible when they are subjected to extreme nanoconfinement. The strength of the repulsion required to induce phase separation increases significantly as confinement increases. We find that this enhanced miscibility is driven by both an increase in entropic penalty upon phase separation and a decrease in enthalpic repulsion with increasing confinement. We relate the change in enthalpy to a reduction in the number of polymer−polymer contacts near nanoparticle surfaces and the change in entropy to a reduction in conformational freedom due to the formation of a polymer−polymer interface near nanoparticle surfaces. Confinement-induced mixing of polymers in nanoparticle packings could enable precise tuning of mechanical and transport properties of nanocomposite films and membranes.

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Phase Separation in Polymer Blends Near a Surface

Cited by 7 publications

References 12 publications

Molecular Conformation and Mobility of Polyamines Adsorbed on Silica Studied by Spin Labeling

Molecular Conformation and Mobility of Polyamines Adsorbed on Silica Studied by Spin Labeling

Phase separation of polymer blends in solution near adsorbing surface

Increases in Miscibility of a Binary Polymer Blend Confined within a Nanoparticle Packing

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