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Zhengang Wang - One of the best experts on this subject based on the ideXlab platform.

  • polyelectrolyte Chain Structure and solution phase behavior
    Macromolecules, 2018
    Co-Authors: Kevin Shen, Zhengang Wang
    Abstract:

    Using a recently developed renormalized Gaussian fluctuation (RGF) field theory that self-consistently accounts for the concentration-dependent coupling between Chain Structure and electrostatic correlations, we study the phase behavior of polyelectrolyte solutions, with a focus on the effects of added salts and Chain Structure. For solutions of a single polyelectrolyte species plus salt, the RGF theory predicts the existence of a loop in the phase boundary at Bjerrum lengths (inverse temperature) below (above) the critical value of the salt-free system. This loop behavior can occur at electrostatic interaction strengths lb/b at which the loop no longer exists for the TPT-1 theory, and at fixed lb/b the loop can persist for infinitely long Chains, in contrast to theories using a fixed-Gaussian Structure (fg-RPA). For systems of oppositely charged (but otherwise symmetric) Chains, we again find that the fg-RPA greatly overpredicts the driving force for phase separation, especially at higher charge fraction...

  • theory of polymer Chains in poor solvent single Chain Structure solution thermodynamics and θ point
    Macromolecules, 2014
    Co-Authors: Rui Wang, Zhengang Wang
    Abstract:

    Using the language of the Flory chi parameter, we develop a theory that unifies the treatment of the single-Chain Structure and the solution thermodynamics of polymers in poor solvents. The Structure of a globule and its melting thermodynamics is examined using the self-consistent filed theory. Our results show that the Chain conformation involves three states prior to the globule-to-coil transition: the fully-collapsed globule, the swollen globule and the molten globule, which are distinguished by the core density and the interfacial thickness. By examining the Chain-length dependence of the melting of the swollen globule, we find universal scaling behavior in the Chain properties near the Theta point. The information of density profile and free energy of the globule is used in the dilute solution thermodynamics to study the phase equilibrium of polymer solution. Our results show different scaling behavior of the solubility of polymers in the dilute solution compared to the F-H theory, both in the chi dependence and the Chain-length dependence. From the perspectives of single Chain Structure and solution thermodynamics, our results verifies the consistency of the Theta point defined by different criteria in the limit of infinite Chain length: the disappearance of the second viral coefficient, the abrupt change in Chain size and the critical point in the phase diagram of the polymer solution. Our results show the value of chi at the Theta point is 0.5 (for the case of equal monomer and solvent volume), which coincides with the value predicted from the F-H theory.

  • theory of polymer Chains in poor solvent single Chain Structure solution thermodynamics and theta point
    arXiv: Soft Condensed Matter, 2014
    Co-Authors: Rui Wang, Zhengang Wang
    Abstract:

    Using the language of the Flory chi parameter, we develop a theory that unifies the treatment of the single-Chain Structure and the solution thermodynamics of polymers in poor solvents. The Structure of a globule and its melting thermodynamics is examined using the self-consistent filed theory. Our results show that the Chain conformation involves three states prior to the globule-to-coil transition: the fully-collapsed globule, the swollen globule and the molten globule, which are distinguished by the core density and the interfacial thickness. By examining the Chain-length dependence of the melting of the swollen globule, we find universal scaling behavior in the Chain properties near the Theta point. The information of density profile and free energy of the globule is used in the dilute solution thermodynamics to study the phase equilibrium of polymer solution. Our results show different scaling behavior of the solubility of polymers in the dilute solution compared to the F-H theory, both in the chi dependence and the Chain-length dependence. From the perspectives of single Chain Structure and solution thermodynamics, our results verifies the consistency of the Theta point defined by different criteria in the limit of infinite Chain length: the disappearance of the second viral coefficient, the abrupt change in Chain size and the critical point in the phase diagram of the polymer solution. Our results show the value of chi at the Theta point is 0.5 (for the case of equal monomer and solvent volume), which coincides with the value predicted from the F-H theory.

Rui Wang - One of the best experts on this subject based on the ideXlab platform.

  • theory of polymer Chains in poor solvent single Chain Structure solution thermodynamics and θ point
    Macromolecules, 2014
    Co-Authors: Rui Wang, Zhengang Wang
    Abstract:

    Using the language of the Flory chi parameter, we develop a theory that unifies the treatment of the single-Chain Structure and the solution thermodynamics of polymers in poor solvents. The Structure of a globule and its melting thermodynamics is examined using the self-consistent filed theory. Our results show that the Chain conformation involves three states prior to the globule-to-coil transition: the fully-collapsed globule, the swollen globule and the molten globule, which are distinguished by the core density and the interfacial thickness. By examining the Chain-length dependence of the melting of the swollen globule, we find universal scaling behavior in the Chain properties near the Theta point. The information of density profile and free energy of the globule is used in the dilute solution thermodynamics to study the phase equilibrium of polymer solution. Our results show different scaling behavior of the solubility of polymers in the dilute solution compared to the F-H theory, both in the chi dependence and the Chain-length dependence. From the perspectives of single Chain Structure and solution thermodynamics, our results verifies the consistency of the Theta point defined by different criteria in the limit of infinite Chain length: the disappearance of the second viral coefficient, the abrupt change in Chain size and the critical point in the phase diagram of the polymer solution. Our results show the value of chi at the Theta point is 0.5 (for the case of equal monomer and solvent volume), which coincides with the value predicted from the F-H theory.

  • theory of polymer Chains in poor solvent single Chain Structure solution thermodynamics and theta point
    arXiv: Soft Condensed Matter, 2014
    Co-Authors: Rui Wang, Zhengang Wang
    Abstract:

    Using the language of the Flory chi parameter, we develop a theory that unifies the treatment of the single-Chain Structure and the solution thermodynamics of polymers in poor solvents. The Structure of a globule and its melting thermodynamics is examined using the self-consistent filed theory. Our results show that the Chain conformation involves three states prior to the globule-to-coil transition: the fully-collapsed globule, the swollen globule and the molten globule, which are distinguished by the core density and the interfacial thickness. By examining the Chain-length dependence of the melting of the swollen globule, we find universal scaling behavior in the Chain properties near the Theta point. The information of density profile and free energy of the globule is used in the dilute solution thermodynamics to study the phase equilibrium of polymer solution. Our results show different scaling behavior of the solubility of polymers in the dilute solution compared to the F-H theory, both in the chi dependence and the Chain-length dependence. From the perspectives of single Chain Structure and solution thermodynamics, our results verifies the consistency of the Theta point defined by different criteria in the limit of infinite Chain length: the disappearance of the second viral coefficient, the abrupt change in Chain size and the critical point in the phase diagram of the polymer solution. Our results show the value of chi at the Theta point is 0.5 (for the case of equal monomer and solvent volume), which coincides with the value predicted from the F-H theory.

J. Dana Honeycutt - One of the best experts on this subject based on the ideXlab platform.

  • Single-Chain Structure in model polyethylene melts
    Macromolecules, 1992
    Co-Authors: John D. Mccoy, Kevin G. Honnell, John G. Curro, Kenneth S. Schweizer, J. Dana Honeycutt
    Abstract:

    The RIS model is usually considered to be an excellent description of the single-Chain Structure of polymer Chains both in the melt and in θ solvents. The manifestation of this single-Chain Structure is the correlation function ω(r), which is the probability that two sites on the same Chain are separated by a distance r. The evaluation of ω(r) from the RIS model requires laborious statistical averages, and, as a consequence, various approrimations of ω(r) are of importance. Understanding the polymer behavior requires n approximate ω(r) which is accurate on all length scales. Such an approximation is presented and compared to both computer simulation and previous, more coarse-grained approaches

R Tao - One of the best experts on this subject based on the ideXlab platform.

  • static shear stress of electrorheological fluids
    Physical Review E, 1993
    Co-Authors: G L Gulley, R Tao
    Abstract:

    We have calculated the static shear stress of an induced electrorheological solid for a single-Chain Structure, double-Chain Structure, triple-Chain Structure, and body-centered tetragonal (bct) lattice. When the shear strain is small, all of these four Structures prefer slanted configurations which will come back to the original configurations if the load is removed. As the shear strain exceeds a yield point, the Structures break into parts which cannot return to the original configurations in a short time. The bct lattice is found to have the strongest shear modulus. The triple-Chain Structure is weaker than the bct lattice, but much stronger than the single-Chain Structure and double-Chain Structure. The single-Chain Structure has the Peierls-Landau instability if the Chain is very long. A double Chain is stronger than a single Chain if the Chains are quite long and the situation is reversed if the Chains are short.

  • static shear stress of electrorheological fluids
    Physical Review A, 1993
    Co-Authors: G L Gulley, R Tao
    Abstract:

    We have calculated the static shear stress of an induced electrorheological solid for a single-Chain Structure, double-Chain Structure, triple-Chain Structure, and body-centered tetragonal (bct) lattice. When the shear strain is small, all of these four Structures prefer slanted configurations which will come back to the original configurations if the load is removed. As the shear strain exceeds a yield point, the Structures break into parts which cannot return to the original configurations in a short time. The bct lattice is found to have the strongest shear modulus. The triple-Chain Structure is weaker than the bct lattice, but much stronger than the single-Chain Structure and double-Chain Structure

Karl T Ulrich - One of the best experts on this subject based on the ideXlab platform.

  • product variety supply Chain Structure and firm performance analysis of the u s bicycle industry
    Management Science, 2001
    Co-Authors: Taylor Randall, Karl T Ulrich
    Abstract:

    Using data from the U.S. bicycle industry, we examine the relation among product variety, supply Chain Structure, and firm performance. Variety imposes two types of costs on a supply Chain:production costs andmarket mediation costs. Production costs include, among other costs, the incremental fixed investments associated with providing additional product variants. Market mediation costs arise because of uncertainty in product demand created by variety. In the presence of demand uncertainty, precisely matching supply with demand is difficult. Market mediation costs include the variety-related inventory holding costs, product mark-down costs occurring when supply exceeds demand, and the costs of lost sales occurring when demand exceeds supply. We analyze product variety at the product attribute level, noting that the relative impact of variety on production and market mediation costs depends to a large extent on the attribute underlying the variety. That is, some types of variety incur high production costs and some types of variety incur high market mediation costs. We characterize supply Chain Structure by the degree to which production facilities are scale-efficient and by the distance of the production facility from the target market. We hypothesize that firms with scale-efficient production (i.e., high-volume firms) will offer types of variety associated with high production costs, and firms with local production will offer types of variety associated with high market mediation costs. This hypothesis implies that there is a coherent way to match product variety with supply Chain Structure. Empirical results suggest that firms which match supply Chain Structure to the type of product variety they offer outperform firms which fail to match such choices.