Modes selection in polymer mixtures undergoing phase separation by photochemical reactions

Tran-Cong, Qui; Kawai, Junji; Endoh, Kouichi

doi:10.1063/1.166406

Cited by 41 publications

(46 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The first group involves phase-separating mixtures of two polymers A and B with which undergo a photoinduced reversible reaction between them. [154][155][156][157][158][159][160][161][162] Since phase separation shares key characteristics with cross-diffusion, we will examine these experiments below when we analyze patterns in simple systems.…”

Section: C Cross-diffusion In Physicochemical Systemsmentioning

confidence: 99%

“…159,160,[176][177][178] Phase separation in binary mixtures is related to cross-diffusion in that A molecules tend to diffuse toward A molecules and B toward B (clustering), and clusters A n diffuse toward regions with lower concentrations of clusters B n and vice versa. Though system (33) is not completely equivalent to a phase-separating system, we can expect Turing patterns in system (33) with appropriate crossdiffusion coefficients when the rate constant k 1 (or k 2 ) is a function of the light intensity.…”

Section: A Simple Linear Systemsmentioning

confidence: 99%

See 1 more Smart Citation

Cross-diffusion and pattern formation in reaction–diffusion systems

Vanag

Epstein

2009

Phys. Chem. Chem. Phys.

265

199

View full text Add to dashboard Cite

Cross-diffusion, the phenomenon in which a gradient in the concentration of one species induces a flux of another chemical species, has generally been neglected in the study of reaction-diffusion systems.We summarize experiments that demonstrate that cross-diffusion coefficients can be quite significant, even exceeding ''normal,'' diagonal diffusion coefficients in magnitude in systems that involve ions, micelles, complex formation, excluded volume effects (e.g., surface or polymer reactions) and other phenomena commonly encountered in situations of interest to chemists. We then demonstrate with a series of model calculations that cross-diffusion can lead to spatial and spatiotemporal pattern formation, even in relatively simple systems. We also show that, in the absence of cross-diffusion among the reacting species, introduction of a nonreactive species that induces appropriate cross-diffusive fluxes with reactive species can lead to pattern formation.

show abstract

Section: C Cross-diffusion In Physicochemical Systemsmentioning

confidence: 99%

Section: A Simple Linear Systemsmentioning

confidence: 99%

Cross-diffusion and pattern formation in reaction–diffusion systems

Vanag

Epstein

2009

Phys. Chem. Chem. Phys.

265

199

View full text Add to dashboard Cite

show abstract

“…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

View full text Add to dashboard Cite

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

show abstract

“…This analog of photoaddressable molecules include photo-responsive molecules that photo-dimerized, such as coumarins and anthracenes; those that allow intra-molecular photo-induced bond formation, such as spiropyrans, and diarylethenes; and those that exhibit photo-isomerization, such as stilbenes, crowded alkenes, and azobenzenes. [17] Tran-Cong-Miyata and coworkers [18][19][20][21] demonstrated the concept of phototuning microphase separated structures in polymer mixtures for a series of trans-stilbene labeled PS and poly(vinyl methyl ether) (PSS/PVME) blends. Upon irradiation, the stilbene moieties on the PSS chains begin to undergo a reversible trans-cis photoisomerization.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Photoisomerizable Block Copolymers by Atom Transfer Radical Polymerization

Huang¹,

Chen²,

Russell³

et al. 2009

Macro Chemistry & Physics

View full text Add to dashboard Cite

A series of polystyrene‐block‐poly(n‐butyl methacrylate) (PS‐b‐PnBMA) diblock copolymers (di‐BCPs) with an azobenzene moiety [trans‐4‐methacryloyloxyazobenzene (MOAB)] in the PnBMA segment was prepared by atom transfer radical polymerization (ATRP). P(nBMA‐co‐MOAB) macroinitiators were prepared by activators regenerated by electron transfer (ARGET) ATRP. The MOAB was slightly more reactive than nBMA, resulting in a weak gradient fashion of copolymer. The macroinitiators were subsequently chain‐extended with styrene. Acceleration of the ATRP rate was observed in the presence of a reducing agent. P(nBMA‐co‐MOAB)‐b‐PS di‐BCPs were obtained with relatively narrow molecular weight distributions ($\overline M _{\rm w}$/$\overline M _{\rm n}$ = 1.16–1.49) and the molecular weights were in good agreement with the theoretical values. The efficiency of photoisomerization of the MOAB units was above 80%. DSC traces showed a single Tg suggesting the block copolymers were miscible before UV irradiation. After UV irradiation, the X‐ray reflectivity measurements showed the beating of two frequencies, indicating the formation of island‐hole structure.magnified image

show abstract

Modes selection in polymer mixtures undergoing phase separation by photochemical reactions

Cited by 41 publications

References 32 publications

Cross-diffusion and pattern formation in reaction–diffusion systems

Cross-diffusion and pattern formation in reaction–diffusion systems

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

Synthesis of Photoisomerizable Block Copolymers by Atom Transfer Radical Polymerization

Contact Info

Product

Resources

About