A generic molecular thermodynamic model for linear and branched polymer solutions in a lattice

Yang, Jingyi; Peng, Changjun; Liu, Honglai; Hu, Ying; Jiang, Jianwen

doi:10.1016/j.fluid.2006.04.012

Cited by 31 publications

(15 citation statements)

References 29 publications

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“…Matsuyama and Tanaka [6], Vause and Walker [7] and Bae et al [8] reported a simple method to represent phase equilibria for the miscibility closed loop behaviors of binary polymer solutions. Recently, Yang et al [9][10][11][12] developed a new lattice model for polymer solutions by combining the molecular simulation with statistical mechanics, several types of phase diagrams such as UCST, LCST, and miscibility loop diagrams are described.…”

Section: Introductionmentioning

confidence: 99%

Closed miscibility loop phase behavior of polymer solutions

Oh¹,

Bae²

2008

Polymer

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Section: Introductionmentioning

confidence: 99%

Closed miscibility loop phase behavior of polymer solutions

Oh¹,

Bae²

2008

Polymer

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“…They attribute the decrease in the critical temperature and the increase in the critical volume fraction to "the simultaneous contraction of the polymer with the degree of branching." 5 In another simulation, Yang et al 8 reported the results of a generic molecular thermodynamic model for the location of the critical point as the degree of branching increased. Their results were comparable with the lattice cluster theory for large N, but found the same qualitative behavior as the MC simulation for T c ͑N͒ and c when N was smaller: an increase in the branching causes an increased polymer miscibility that is seen as a decrease in the critical temperature and increase in critical volume fraction.…”

Section: Introductionmentioning

confidence: 99%

Universality in eight-arm star polystyrene and methylcyclohexane mixtures near the critical point

Jacobs

Braganza

Brinck

et al. 2007

The Journal of Chemical Physics

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Measurements of the coexistence curve and turbidity were made on different molecular mass samples of the branched polymer-solvent system eight-arm star polystyrene in methylcyclohexane near its critical point. We confirmed that these systems belong in the Ising universality class. The location of the critical temperature and composition as well as the correlation length, susceptibility, and coexistence curve amplitudes were found to depend on molecular mass and the degree of branching. The coexistence curve diameter had an asymmetry that followed a "complete scaling" approach. All the coexistence curve data could be scaled onto a common curve with one adjustable parameter. We found the coexistence curve amplitude to be about 12% larger for branched than linear polystyrenes of the same molecular mass in either solvent cyclohexane or methylcyclohexane. The two-scale-factor universality ratio R was found to be independent of molecular mass or degree of branching.

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“…Recent Monte Carlo simulation results also fail to describe the experimental data. 8,9 In this situation, a phenomenological approach to the problem may be useful as an alternate. [10][11][12] In our previous work, Terao et al…”

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confidence: 99%

Light Scattering and Phase Separation Studies on Cyclohexane Solutions of Six-Arm Star Polystyrene†

Tasaka

Okumoto

Nakamura

et al. 2008

Polym J

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Light scattering and phase separation experiments were performed for four six-arm star polystyrene (6SPS) samples with weight-average molecular weights M w of 9:62 Â 10 4 to 1:16 Â 10 6 in cyclohexane below the theta temperature (34.5 C). From the former experiment, the apparent second virial coefficient J was obtained as functions of the polymer volume fraction and temperature T, along with the spinodals. In the latter experiment, the concentrations of coexisting two phases were determined as functions of T. The critical point T c determined from the coexisting curve was lower than that for fourarm star polystyrene (4SPS) when compared at the same M w . As was the case for 4SPS and linear polystyrene in cyclohexane, J for 6SPS at each T in a region of large was represented by a universal function of =P 0:1 regardless of P (the volume of the polymer chain relative to that of the solvent molecule), although it differed from the common function previously found for the other two types of polystyrene. It was concluded that the solubility of 6SPS higher than that of 4SPS in cyclohexane as indicated by the lower critical point is attributable to the chain-end effect.KEY WORDS: Star Polymer / Phase Separation / Chemical Potential / Binodal / Spinodal / Critical Point / Polystyrene / It is known that the phase separation temperature for star polymers in poor solvents are lower than that for the corresponding linear polymer with the same molecular weight and the same chemical structure. [1][2][3][4][5][6] This cannot be explained by theories invoking the Flory-Huggins type 7 mean-field approximation, but at present, there exists no molecular theory that explains the phase behavior of branched molecules. Recent Monte Carlo simulation results also fail to describe the experimental data. 8,9 In this situation, a phenomenological approach to the problem may be useful as an alternate. [10][11][12] In our previous work, Terao et al.4 carried out light scattering and phase separation experiments on four-arm star polystyrene (PS) in cyclohexane below the theta point Â (34.5 C). Their light scattering data showed that the apparent second virial coefficient J at a fixed temperature T in a region of high polymer volume fraction can be represented by a universal function of =P 0:1 regardless of molecular weight and that the same function is also applicable to linear PS in cyclohexane, where P is the relative chain length (the volume of the polymer chain relative to that of the solvent molecule). The difference in J between four-arm star and linear PS's appeared only at low . Thus, it was concluded that the difference in the chemical potential of the solvent in the low region is responsible for the difference in phase separation behavior between the two polymers.The present study was undertaken as an extension of the previous work to six-arm star PS in cyclohexane below Â to examine the J function behavior and the phase diagrams in relation to four-arm star and linear PS's. Light scattering and phase separation data obtained as func...

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A generic molecular thermodynamic model for linear and branched polymer solutions in a lattice

Cited by 31 publications

References 29 publications

Closed miscibility loop phase behavior of polymer solutions

Closed miscibility loop phase behavior of polymer solutions

Universality in eight-arm star polystyrene and methylcyclohexane mixtures near the critical point

Light Scattering and Phase Separation Studies on Cyclohexane Solutions of Six-Arm Star Polystyrene†

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