Phase Separation of a Polymer Mixture Driven by a Gradient of Light Intensity

Nishioka, Hiroya; Kida, Kaname; Yano, Okihito; Tran-Cong, Qui

doi:10.1021/ma992088a

Cited by 27 publications

(30 citation statements)

References 10 publications

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“…Light in the UV range was applied on polymer blends of stilbene-labeled polystyrene and polyvinylmethylether (PSS/PVME). This caused phase separation of the blend because trans→cis transition changes both the volume and the enthalpic interaction between the polymers (Nishioka et al, 2000). In addition, photochemical reaction was induced in anthracene-labeled polystyrene-PVME blends irradiated by periodic UV light.…”

Section: Light-induced Phase Transitions In Mixturesmentioning

confidence: 99%

Colloquium: Phase transitions in polymers and liquids in electric fields

Tsori

2009

Rev. Mod. Phys.

101

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The structure and thermodynamic state of a system changes under the influence of external electric fields. Neutral systems are characterized by their dielectric constant ε, while charged ones also by their charge distribution. In this Colloquium several phenomena occurring in soft-matter systems in spatially uniform and nonuniform fields are surveyed and the role of the conductivity σ and the linear or nonlinear dependency of ε on composition are identified. Uniform electric fields are responsible for elongation of droplets, for destabilization of interfaces between two liquids, and for mixing effects in liquid mixtures. Electric fields, when acting on phases with mesoscopic order, also give rise to block copolymer orientation, to destabilization of polymer-polymer interfaces, and to order-order phase transitions. The role of linear and nonlinear dependences of ε on composition will be elucidated in these systems. In addition to the dielectric anisotropy, existence of a finite conductivity leads to appearance of large stresses when these systems are subject to external fields and usually to a reduction in the voltages required for the instabilities or phase transitions to occur. Finally, phase transitions which occur in nonuniform fields are described and emphasis on the importance of ε and σ is given.

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Section: Light-induced Phase Transitions In Mixturesmentioning

confidence: 99%

Colloquium: Phase transitions in polymers and liquids in electric fields

Tsori

2009

Rev. Mod. Phys.

101

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“…However, this method, together with irradiation using UV light intensity with a lateral gradient [62], can simply provide graded structures along the direction of propagation of light. In order to generate morphologies with arbitrary distribution of characteristic length scales in 3D, we have developed the so-called computer-assisted irradiation (CAI) method as described below.…”

Section: Morphology With Arbitrary Symmetry and Distribution Of Lengtmentioning

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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“…There are several examples of reaction-induced phase separation in photosen sitive systems. Blends of -stilbene labeled polystyrene and poly(vinyl methyl ether) (PSS/PVME) constitute one well-known example [16][17][18][19][20][21]. Upon irradiation, the stilbene moieties on the PSS chains undergo a reversible trans-cis photo isomerization.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, a reversible chemical reaction and phase separation taking place simultaneously within this binary blend. Other photosensitive pendent groups can also be used to yield a similar behavior [16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Modeling the Self‐Assembly of Ternary Blends that Encompass Photosensitive Chemical Reactions: Creating Defect‐Free, Hierarchically Ordered Materials

Kuksenok

Travasso

Dayal

et al. 2010

Encyclopedia of Polymer Blends

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There is a significant drive to harness self-assembling polymers in various micro electronic devices; the fact that the materials are polymers reduces the cost of fabrication and the self-assembling aspect reduces the number of processing steps, which again reduces cost. However, several critical requirements, typically, must be met before self-assembling polymers can be implemented in the production of electronic components. In particular, the following conditions must be satisfied: 1) the system should form hierarchical structures, with some domains being on the sub-micron or nanoscale scale, while other domains are on the micron scale; 2) the material should be defect free on the mm to cm length scale; 3) it should be possible to form a wide variety of patterns.Researchers have addressed these issues, particularly conditions (2) and (3), by directing the self-organization of block copolymer films with an underlying patterned substrate [1][2][3][4][5]. In this manner, the systems exhibited nanoscale features and macroscopic order (with ordered regions that are 1 cm 2 in size) [2][3][4]. In addition, the substrate could be patterned into non-regular shapes and the overlying copoly mers or copolymer/homopolymer mixture could be made to replicate the underlying design [2][3][4].In recent studies [6-8], we proposed an alternative approach that does not rely on self-assembling copolymers to address the issues listed above. In particular, we used a computational model to demonstrate how homopolymer blends undergoing a photo-induced chemical reaction can yield structures with long-range order in thin films [6, 7] and bulk materials [8]. The process is initiated by shining a spatially uniform light over a photosensitive AB binary homopolymer blend, which thereby undergoes both a reversible chemical reaction and phase separation. We then introduce a well-collimated, higher intensity light source. By rastering this secondary light over the sample we could comb out any defects in the material and thereby create spatially regular, periodic structures. These binary structures resemble either the lamellar or hexagonal phases of microphase-separated diblock copolymers [9, 10].Edited by Avraam I. Isayev

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Phase Separation of a Polymer Mixture Driven by a Gradient of Light Intensity

Cited by 27 publications

References 10 publications

Colloquium: Phase transitions in polymers and liquids in electric fields

Colloquium: Phase transitions in polymers and liquids in electric fields

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

Modeling the Self‐Assembly of Ternary Blends that Encompass Photosensitive Chemical Reactions: Creating Defect‐Free, Hierarchically Ordered Materials

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