Positive feedback driven by concentration fluctuations in asymmetrically photo-cross-linked polymer mixtures

Tran-Cong, Qui; Harada, Asuka; Kataoka, K.; Ohta, Takashi; Urakawa, Osamu

doi:10.1103/physreve.55.r6340

Cited by 19 publications

(16 citation statements)

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“…The process of the phase separation depends on characteristic parameters such as self-and inter-diffusion coefficients, and Flory interaction parameters. The rate of the phase separation is also connected with the rates of chemical reactions and can be controlled by the crosslinking density of polymers during a process of IPNs preparation [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Semi-interpenetrating polymer networks based on polyurethane and poly(2-hydroxyethyl methacrylate): Dielectric study of relaxation behavior

Karabanova¹,

Boiteux²,

Seytre³

et al. 2009

Journal of Non-Crystalline Solids

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Section: Introductionmentioning

confidence: 99%

Semi-interpenetrating polymer networks based on polyurethane and poly(2-hydroxyethyl methacrylate): Dielectric study of relaxation behavior

Karabanova¹,

Boiteux²,

Seytre³

et al. 2009

Journal of Non-Crystalline Solids

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“…͑16͒ does not hold at temperatures close to the phase boundary where the autocatalytic behavior of the crosslinking reaction was found recently. 28 From the experimental results described above, we conclude that the A-A type of cross-linking reactions induced inside the spinodal as well as in the one-phase regions of binary polymer mixtures suppress the long-wavelength fluctuations in the reacting mixture. These experimental results suggest that morphologies with various intrinsic length scales can be obtained by appropriately adjusting the competition between the reaction and phase separation.…”

Section: A Phase Separation Of Binary Polymer Mixtures With the A-a mentioning

confidence: 77%

Modes selection in polymer mixtures undergoing phase separation by photochemical reactions

Tran-Cong

Kawai

Endoh

1999

Chaos: An Interdisciplinary Journal of Nonlinear Science

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Phase separation kinetics and morphology of binary polymer mixtures (A/B) in the presence of photochemical reactions were investigated by using phase-contrast optical microscopy combined with digital image analysis. The polymers were chemically designed in such a way that two types of chemical reactions, intermolecular photodimerization and intramolecular photoisomerization, of polymer segments can be induced and controled by irradiation with ultraviolet light. Unlike the conventional case, the phase separation in the presence of these reactions is spontaneously frozen due to the suppression of the long-wavelength instabilities, resulting in stationary spatial structures with intrinsic periodicities. These characteristic length scales are determined by the competition between the two antagonistic interactions: phase separation as a relatively short-range activation and the photochemical reaction as a long-range inhibition. Furthermore, it was found that the spatial symmetry breaking of concentration fluctuations can emerge from the elastic stress associated with the nonhomogeneous kinetics of the reactions. Experimental data obtained with three types of reactions: A-A only cross-link, A-A and B-B simultaneous cross-links and the reversible A<-->B photoisomerization are described. These results do not only indicate that combination of chemical reactions and phase separation could provide a novel method to control the morphology of multiphase polymer materials, but also suggest that photoreactive polymers can be used as a chemical system to study the mode-selection process in polymers far from thermodynamic equilibrium. (c) 1999 American Institute of Physics.

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“…Also, an alternative approach has been followed for the analysis of the couplings between reaction and phase separation at the surface of a catalyst [28]. However, from the macromolecular viewpoint, the reaction/diffusion formalism described above does not take into account several important polymer effects such as the feedback of the chemical reactions on the free energy of the mixture and vice versa [29][30][31], in particular, the reaction-induced elasticity, as shown later. Therefore, these theories are still far from the stage of quantitative comparison with the experimental data obtained for polymer systems [32].…”

Section: Phase Separation Of Reacting Mixturesmentioning

confidence: 99%

Reaction‐Induced Phase Separation of Polymeric Systems under Stationary Nonequilibrium Conditions

Nakanishi

Fujiki

Van‐Pham

et al. 2010

Nonlinear Dynamics With Polymers

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Cong-Miyata IntroductionFor most cases, materials processing is carried out under various conditions far from equilibrium where the temperature, concentration, or pressure is not constant, but is, in general, a function of time and space. Under such stationary nonequilibrium conditions, coupling among the different variables such as diffusion, concentration, temperature, density, or surface tension distribution can lead to a wide variety of instabilities such as double diffusion, Mullins-Sekerka, RayleighBenard, Rayleigh-Taylor, and so on [1-3]. As a consequence, for a physicochemical system undergoing phase separation far from thermodynamic equilibrium, one can expect the emergence of various exotic morphologies whereby functional materials can be designed and utilized.In this chapter, we will show that, by using ultraviolet (UV) irradiation to induce and maintain phase separation under stationary nonequilibrium conditions, morphologies that cannot be generated under thermal equilibrium conditions can be produced and controlled by taking advantage of the competition between phase separation and photochemical reactions. At first, theories and numerical calculation of phase separation kinetics in both nonreacting and reacting systems are briefly overviewed, together with the experimental results on reaction kinetics in polymeric mixtures. Here, the nonuniform kinetics observed for mixtures in both the bulk and liquid states containing monomers is summarized. Emphasis is particularly given for the autocatalytic behavior of the reaction and its consequence on the phase separation kinetics and the resulting morphology. By taking advantage of the gradient of light intensity in an irradiated sample, morphology with spatially graded structures is constructed and controlled. Emergence of an elastic strain field accompanying the cross-linking process in polymer mixtures is monitored and analyzed by using Mach-Zehnder interferometry. The development and relaxation of this reaction-induced strain field are described, together with its influence on the morphology of the reacting polymer mixtures. Finally, results on the temporal modulation experiments of phase separation are briefly summarized. The conclusions are provided at the end of this chapter, together with some Nonlinear Dynamics with Polymers: Fundamentals, Methods and Applications. Edited by John A. Pojman and Qui Tran-Cong-Miyata

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Positive feedback driven by concentration fluctuations in asymmetrically photo-cross-linked polymer mixtures

Cited by 19 publications

References 0 publications

Semi-interpenetrating polymer networks based on polyurethane and poly(2-hydroxyethyl methacrylate): Dielectric study of relaxation behavior

Semi-interpenetrating polymer networks based on polyurethane and poly(2-hydroxyethyl methacrylate): Dielectric study of relaxation behavior

Modes selection in polymer mixtures undergoing phase separation by photochemical reactions

Reaction‐Induced Phase Separation of Polymeric Systems under Stationary Nonequilibrium Conditions

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