Cloud-point curves of polymer solutions from thermooptical measurements

Bae, Young Chan; Lambert, Stephen M.; Soane, David S.; Prausnitz, John M.

doi:10.1021/ma00015a024

Cited by 239 publications

(274 citation statements)

References 5 publications

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“…In addition, the number of hydrogen bonds formed, which is responsible for the phase separation, decreases with increasing temperature. This type of closedloop miscibility curve has been found in different binary solutions including nicotine/water and poly(ethylene glycol)/water [7,8], as well as by modeling of binary mixtures containing hydrogen-bonded molecules [12,13,14].…”

Section: Introductionmentioning

confidence: 67%

“…7). We have repeated this procedure for the system poly(ethylene glycol) in water, which has a critical density of ρ * p = 0.15 and a much larger molecular weight M w = 3350 [8], and which resulted in a similar agreement with the experimental curve.…”

Section: Figmentioning

confidence: 73%

“…(8). This leads to a relative transition probability for configuration {n ′ i } from a previous one {n i } which depends on the difference in free energy of the two configurations…”

Section: Monte Carlo Simulationmentioning

confidence: 99%

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Hydrophobic Interaction Model for Upper and Lower Critical Solution Temperatures

Moelbert

Rios

2003

Macromolecules

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Hydration of hydrophobic solutes in water is the cause of different phenomena, including the hydrophobic heat-capacity anomaly, which are not yet fully understood. Because of its topicality, there has recently been growing interest in the mechanism of hydrophobic aggregation, and in the physics on which it is based. In this study we use a simple yet powerful mixture model for water, an adapted two-state Muller-Lee-Graziano model, to describe the energy levels of water molecules as a function of their proximity to non-polar solute molecules. The model is shown to provide an appropriate description of many-body interactions between the hydrophobic solute particles. The solubility and aggregation of hydrophobic substances is studied by evaluating detailed Monte Carlo simulations in the vicinity of the first-order aggregation phase transition. A closed-loop coexistence curve is found, which is consistent with a mean-field calculation carried out for the same system. In addition, the destabilizing effect of a chaotropic substance in the solution is studied by suitable modification of the MLG model. These findings suggest that a simple model for the hydrophobic interaction may contain the primary physical processes involved in hydrophobic aggregation and in the chaotropic effect.

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Section: Introductionmentioning

confidence: 67%

Section: Figmentioning

confidence: 73%

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Hydrophobic Interaction Model for Upper and Lower Critical Solution Temperatures

Moelbert

Rios

2003

Macromolecules

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“…Nowadays it is accepted that the dependence of g on concentration mainly arises from the disparities in size and shape of the solvent molecules and the polymer segments. According to Staverman [6], it is possible to write the functionality of g as Equation (1): (1) where c is a constant determined from Bondi studies [8][9][10] and D(T) accounts for the temperature dependence in the form of Equation (2): (2) On the other hand, χ→g, just when the volume fraction of component 2 φ 2 →1, or at infinite dilution of solvent, which are the conditions fulfilled by the inverse gas chromatography technique [5], although, it is also used (Equation (3)) when analyzing the thermodynamics of the phase separation during polymerization of a thermoset system into a thermoplastic matrix [11,12]. (3) Occasionally, and in order to adjust the experimental results, the interaction function, dependent on both temperature and composition, can be written [5,[13][14][15] as Equation (4): (4) where α is an empirical entropy correction [5] given by Equation (5): (5) Obviously, this new g value yields a different expression for χ, (Equation (6)) [15]: (6) Moreover, an even more complex function to express the χ temperature and concentration dependence has been found (Equation (7)) [16]: (7) where c i (i = 1, 2), D and d being adjustable parameters.…”

Section: Introductionmentioning

confidence: 99%

Determination of χ from liquid-liquid phase data in ternary polymer systems (solvent/polymer/polymer) with hydrogen bonding

Figueruelo¹,

Garcı́a-Lopera

Monzó³

et al. 2008

Express Polym. Lett.

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Abstract. Two different models accounting for the dependences of χ and g interaction parameters on both temperature and composition have been applied to different ternary polymer systems (TPS) solvent(1)/polymer(2)/polymer(3). The analyzed TPS have consisted on ten different polymer mixtures in chloroform as common solvent that can specifically interact via hydrogen bond. Experimental ternary phase diagrams determined by liquid chromatography were taken from literature. The application of the two models to the experimental data have served to obtain χij and gij interaction parameters for all the binary ij (ij = 12, 13, 23) interactions established between the three components of the system, with simplified mathematical procedures. The results have shown a fair agreement between the calculated and the literature values, at least when the model containing an empirical entropy correction is used. Moreover, the evaluated interaction parameters follow the expected behaviour as the content of the H-donor polymer in the mixture is raised and are also in good accordance with experimental viscometric data.

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“…[4][5][6][7] Conventional LCST polymer solutions in organic media have critical temperatures that are higher than the boiling points (BPs) of the solvents. [8][9][10][11][12][13][14] These reported systems can exhibit LCST-type phase behavior under some extreme conditions, for example, in sealed highpressure cells above the BP of the solvent or using considerably highmolecular-weight polymers. Some theories have been proposed to explain or predict this type of LCST-type phase behavior.…”

Section: Introductionmentioning

confidence: 98%

LCST-type phase behavior of poly(2-chloroethyl vinyl ether-alt-maleic anhydride) in n-butyl acetate

Liu

Guo

Inomata

2011

Polym J

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Novel polymer solutions exhibiting lower critical solution temperatures (LCSTs) have been studied. An alternating copolymer of 2-chloroethyl vinyl ether and maleic anhydride was synthesized through free-radical solution polymerization. This copolymer can exhibit LCST-type phase behavior in n-butyl acetate (BuAc) under relatively mild conditions at temperatures sufficiently below its boiling point. The effects of molecular weight, polymer concentration and addition of cosolvent on the polymer solution's cloud point temperature (T cp ) were investigated. The T cp value was nearly constant over a wide range of concentrations and increased when the polymer concentration was reduced below a certain value. The experimental LCST-type phase diagram can be reasonably described by Flory-Huggins theory. The addition of non-solvents could reduce the T cp of the polymer solution in BuAc, whereas the addition of good solvents could increase the T cp . These LCST-type phase behaviors may be attributed to specific polar interactions between the polymer and the solvent. INTRODUCTIONLower critical solution temperature (LCST)-type phase behavior in polymer solutions has been attracting a great deal of attention over the past decade. Polymers that exhibit LCST are a class of stimuli-sensitive polymers that are soluble at temperatures below the LCST and become insoluble above the LCST. Many studies have focused on LCST-type phase behavior in aqueous polymer solutions, and many theories and applications have been developed. 1-3 Today, LCST-type phase behavior of polymers in nonaqueous media is also attracting interest as an opportunity for research and development of smart materials. For example, LCST polymer solutions of thermoresponsive polymer/ionic liquid systems have been reported. [4][5][6][7] Conventional LCST polymer solutions in organic media have critical temperatures that are higher than the boiling points (BPs) of the solvents. [8][9][10][11][12][13][14] These reported systems can exhibit LCST-type phase behavior under some extreme conditions, for example, in sealed highpressure cells above the BP of the solvent or using considerably highmolecular-weight polymers. Some theories have been proposed to explain or predict this type of LCST-type phase behavior. [15][16][17] In freevolume theories, the difference between the densities or the expansion coefficients of the polymer and the solvent above the solvent's BP is proposed to cause phase separation at elevated temperatures. 17 Because these conditions are inconvenient to study, a novel polymer/organic media solution that can present LCST under mild

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Cloud-point curves of polymer solutions from thermooptical measurements

Cited by 239 publications

References 5 publications

Hydrophobic Interaction Model for Upper and Lower Critical Solution Temperatures

Hydrophobic Interaction Model for Upper and Lower Critical Solution Temperatures

Determination of χ from liquid-liquid phase data in ternary polymer systems (solvent/polymer/polymer) with hydrogen bonding

LCST-type phase behavior of poly(2-chloroethyl vinyl ether-alt-maleic anhydride) in n-butyl acetate

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