Dimensional Crossover in the Phase Separation Kinetics of Thin Polymer Blend Films

Sung, Li Piin; Karim, Alamgir; Douglas, Jack F.; Han, Charles C.

doi:10.1103/physrevlett.76.4368

Cited by 200 publications

(229 citation statements)

References 32 publications

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“…However, a full self-stratification pathway leading to equilibrium bilayer morphology is possible only for antisymmetric surface-fields [3]. In both cases self-stratification can occur for blend films thicker that the wavelength of composition waves [64].…”

Section: Self-stratification (S-s)mentioning

confidence: 99%

Surface-directed phase separation in nanometer polymer films: self-stratification and pattern replication

et al. 2002

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Phase separation occurs in thin films of polymer blends when molecular mobility is promoted by a temperature above the glass transition but inside the twophase region (temperature quench), or a common solvent added to the polymers (solvent quench). This phenomenon can be altered by a homogeneous surface or pre-patterned substrate, resulting, e.g., in self-stratification or pattern replication, respectively. Such self-organisation processes ordering polymer phases were observed for model polymer blends (deuterated/hydrogenated polystyrene, dPS/hPS, and deuterated/partially brominated PS, dPS/PBrS, both with hPSpolyisoprene diblocks added; dPS/poly(vinylpyridine) and PBrS/PVP) with highresolution ion beam techniques (Nuclear Reaction Analysis, profiling and mapping mode of dynamic Secondary Ion Mass Spectrometry) and Atomic Force Microscopy. The self-stratification process is strongly affected by both the range as well as the strength of the surface/polymer interactions. This is illustrated for the temperature-quenched blends with surface-active copolymer additives tuning the interactions exerted by both external surfaces. The pattern transfer from the substrate to the films is demonstrated for the solvent-quenched blends. Patterndirected composition variations (SIMS maps) coincide with free surface undulations (AFM images). The most effective pattern replication is achieved for the length scale of phase domain morphology comparable with the pattern periodicity and for carefully adjusted polymer/substrate interactions.

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Section: Self-stratification (S-s)mentioning

confidence: 99%

Surface-directed phase separation in nanometer polymer films: self-stratification and pattern replication

et al. 2002

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“…A problem of active current research in nano-technology, for example, is the tailoring of thin polymer films on surfaces [1,2]. Spontaneous phase separation processes of incompatible polymer blends may be used to translate a chemical pattern on the surface (as e.g.…”

Section: Introductionmentioning

confidence: 99%

Soft ellipsoid model for Gaussian polymer chains

Eurich

Maass

2001

The Journal of Chemical Physics

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A soft ellipsoid model for Gaussian polymer chains is studied, following an idea proposed by Murat and Kremer [J. Chem. Phys. 108, 4340 (1998)]. In this model chain molecules are mapped onto ellipsoids with certain shapes, and to each shape a monomer density is assigned. In the first part of the work, the probabilities for the shapes and the associated monomer densities are studied in detail for Gaussian chains. Both quantities are expressed in terms of simple approximate formulae. The free energy of a system composed of many ellipsoids is given by an intramolecular part accounting for the internal degrees of freedom and an intermolecular part following from pair interactions between the monomer densities. Structural and kinetic properties of both homogeneous systems and binary mixtures are subsequently studied by Monte-Carlo simulations. It is shown that the model provides a powerful phenomenological approach for investigating polymeric systems on semi-macroscopic time and length scales.

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“…The phase separation and dewetting of other films with different thickness were morphologically similar. The phase separation pattern is formed at very early stage, but no obviously bicontinuous spinodal decomposition structure [13][14][15] was observed in the early stage in these films. Colour change in Figure 1a is a result of phase separation and fluctuation in surface height.…”

Section: Resultsmentioning

confidence: 99%

Phase Separation and Dewetting Induced Surface Pattern in PS/PMMA Blend Films

Xiong

Shi

Tian

2005

Polym J

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ABSTRACT:The pattern evolution of phase separation and dewetting of PS/PMMA blend thin films at 160 C were observed by optical video microscopy and atomic force microscopy (AFM). The results show that the PMMA wetting component is driven toward the substrate, and the PS dewetting component is driven toward the surface by pressure caused by phase separation and wetting. At the late stage of the process, irregular shapes of PS islands evolve into round droplets. A cross-section of the interface between the PS and PMMA after phase separation was observed by AFM for the first time. This shows that the PS component extends considerably into the PMMA substrate layer and a trench was observed inside and outside the PMMA rim, respectively. This confirms the notion of a deformable interface between the two materials. [DOI 10.1295/polymj.37.560] KEY WORDS PS/PMMA Blend Films / Phase Separation / Dewetting / The structure and properties of thin blend films are governed by interplay between phase separation and surface segregation driven by polymer-surface interactions. This is important for applications because commercial films are normally comprised of multiple polymer species, solvent, and additives, leading to numerous complex phase separation morphologies and film properties. As a function of blend composition and polymer-polymer interaction parameter different phase separation morphologies have been observed in bulk samples. In the state of a thin film, with a thickness below a critical film thickness, the surface directed spinodal decomposition of polymers is suppressed and phase separation perpendicular to the interface results. The interplay between phase separation and dewetting increases the variety of accessible surface morphologies. The time scales of dewetting and phase separation are different and depend on the internal interaction.1-8 However, understanding of phase evolution in blend films has not yet been achieved in details, in part due to the complex interplay between wetting, phase separation, capillary fluctuations and coarsening and roughening, respectively.Polystyrene (PS) and poly(methylmethacrylate) (PMMA) are classic model systems in polymer science, and numerous studies have been recently been undertaken. [9][10][11][12] This report studies the phase separation and dewetting of PS and PMMA blend films with different thickness, using optical video microscopy in situ during annealing. For the first time, we report the interface characteristic of PS/PMMA in the final stage of phase separation. EXPERIMENTALFirst, PS and PMMA were dissolved in toluene. The polymers had molecular weights M w ¼ 60500 g/mol (PS), and M w ¼ 62500 g/mol (PMMA) and polydispersities M w =M n ¼ 1:07 (PS) and M w =M n ¼ 1:12 (PMMA). The total polymer concentration was prepared first at 3% and then part of the solution was diluted to 2% and 1%. The PS mass fraction was fixed at 0.50. Thin films of the polymer blends were formed by placing a droplet of the solution onto 1 cm Â 1 cm Si(001) with the native oxide layer present (...

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Dimensional Crossover in the Phase Separation Kinetics of Thin Polymer Blend Films

Cited by 200 publications

References 32 publications

Surface-directed phase separation in nanometer polymer films: self-stratification and pattern replication

Surface-directed phase separation in nanometer polymer films: self-stratification and pattern replication

Soft ellipsoid model for Gaussian polymer chains

Phase Separation and Dewetting Induced Surface Pattern in PS/PMMA Blend Films

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