Statistical thermodynamics of polydisperse polymer systems in the framework of lattice fluid model: Effect of molecular weight and its distribution on the spinodal in polymer solution

Yang, Jian; Sun, Zhaoyan; Jiang, Wei; An, Lijia

doi:10.1063/1.1424320

Cited by 9 publications

(14 citation statements)

References 31 publications

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“…17 The polydispersity of polymers can also change the phase separation temperature. [35][36][37] Increase in the polydispersity index enlarges the phase separation area and shis the LCST to lower temperatures. The polydispersity effect weakens with the increase of molecular weight.…”

Section: Phase Diagram and Morphological Observationmentioning

confidence: 99%

Anomalous phase separation behavior in dynamically asymmetric LCST polymer blends

2014

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The interplay of thermodynamic forces and self-generated stresses induced in different compositions, and at different quench depths on the phase behavior of dynamically asymmetric PS/PVME blends are studied.The thermodynamic phase diagram is obtained from dynamic temperature sweep experiments. Phase contrast optical microscopy and rheological measurements including linear viscoelastic behavior and the stress growth behavior are employed to investigate the time evolution of the different phase-separating morphologies. At an intermediate quench depth of 14 C, in addition to thermodynamically controlled phase separation mechanisms (nucleation and growth, NG, and spinodal decomposition, SD), three different kinds of phase separation behavior are induced by transient gel formation due to self-induced stresses in the early stage of phase separation: (i) conventional viscoelastic phase separation (VPS), (ii) nucleation of aggregate-like PS-rich phase and subsequent formation of a percolated network by coalescence, and (iii) nucleation of an aggregate-like PS-rich phase while the dispersed-matrix morphology is preserved in the later stages of phase separation. While it is generally accepted that VPS occurs at deep quench depths, we observe the VPS mechanism at shallow quench depths which is attributed to dynamic heterogeneity in the phase-separated domains. A dynamic phase diagram which shows the effect of dynamic asymmetry on phase behavior is proposed.

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Section: Phase Diagram and Morphological Observationmentioning

confidence: 99%

Anomalous phase separation behavior in dynamically asymmetric LCST polymer blends

2014

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“…In our previous paper, the effects of polydispersity on the spinodal in polymer solutions were studied by using the Sanchez−Lacombe lattice fluid theory (SLLFT). − It is well-known that the behavior of the polymer in mixtures is much different from that in solutions. However, the study in this area is limited by the complexity of the mixture, because the system may contain thousands of components.…”

Section: Introductionmentioning

confidence: 99%

What Has Brought on the Effects of Number-Average Molecular Weight on the Spinodals in Polymer Mixtures?

et al. 2002

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On the basis of the thermodynamics of Gibbs, the spinodal for the quasibinary system was derived in the framework of the Sanchez-Lacombe lattice fluid theory. All of the spinodals were calculated based on a model polydisperse polymer mixture, where each polymer contains three different molecular weight subcomponents. According to our calculations, the spinodal depends on both weight-average (M h w ) and numberaverage (M h n ) molecular weights, whereas that of the z-average molecular weight is invisible. Moreover, the extreme of the spinodal decreases when the polydispersity index (η ) M h w /M h n ) of the polymer increases. The effect of polydispersity on the spinodal decreases when the molecular weight gets larger and can be negligible at a certain large molecular weight. It is well-known that the influence of polydispersity on the phase equilibrium (coexisting curve, cloud point curves) is much more pronounced than on the spinodal. The effect of M h n on the spinodal is discussed as it results from the infuluence of composition temperatures, molecular weight, and the latter's distribution on free volume. An approximate expression, which is in the assumptions of υ* ) υ 1 / ) υ 2 / and 1/r f 0 for both of the polymers, was also derived for simplification. It can be used in high molecular weight, although it failed to make visible the effect of number-average molecular weight on the spinodal.

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“…It has been shown that for disperse samples the higher weight fractions have a greater influence on the cloud point. 62,63 This set us to explore the phase separation of binary polymer blends in DOP, where we used mixtures of two of different chemical composition, and thus different cloud points. The idea was to incrementally regulate the level of opacity.…”

Section: Phase Separation Behaviour Of Polystyrene In Phthalate and Nonphthalate Plasticizersmentioning

confidence: 99%

Thermotropic Icy Road Sign with Light Scattering and Fluorescence Response

Booth¹,

Young²,

A³

et al. 2021

Preprint

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<div> <div> <div> <p>Prototypes of flexible, electricity-free, ice warning signs for roads and pavements have been developed. A thermotropic response in the form of an upper critical solution (UCST) type phase separation targeted near the freezing point of water manifests itself through light scattering as a clear-to-opaque transition. It is simultaneously amplified by an enhanced photoluminescence effect. The conceptual road sign application is a multi-lamellar flexible strip with an active layer of a polystyrene-based solution. The solvent is a plasticizer, here either dioctylphthalate (DOP) or its alternative 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH). A collection of styrene-based macromolecules were made by free radical (co)polymerization, varying molecular weight and monomer feed composition. UCST type phase diagrams for the polymer solutions were constructed from cloud point data measured by a bespoke photographic set-up, in which up to 30 samples were measured simultaneously using both light scattering, that is opacity, and fluorescence. For the latter, the concept of restricted motion enhanced photoluminescence, often referred to as aggregation-induced emission (AIE), was used. Polystyrene labelled with tetraphenylethylene (TPE) was used for this. The contrast between ‘ON’ and ‘OFF’ states in the prototype ice warning signs was optimized by tuning the polymer concentration and the active layer thickness. Our prototype signs show full reversibility over many temperature cycles. We believe the concept can be of wider use in electricity-free signs and labels. </p> </div> </div> </div>

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Statistical thermodynamics of polydisperse polymer systems in the framework of lattice fluid model: Effect of molecular weight and its distribution on the spinodal in polymer solution

Cited by 9 publications

References 31 publications

Anomalous phase separation behavior in dynamically asymmetric LCST polymer blends

Anomalous phase separation behavior in dynamically asymmetric LCST polymer blends

What Has Brought on the Effects of Number-Average Molecular Weight on the Spinodals in Polymer Mixtures?

Thermotropic Icy Road Sign with Light Scattering and Fluorescence Response

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