Stability of Order in Solvent-Annealed Block Copolymer Thin Films

Niu, Sanjun; Saraf, Ravi F.

doi:10.1021/ma0212792

Cited by 58 publications

(54 citation statements)

References 24 publications

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“…Krausch and coworkers demonstrated both that the choice of solvents dramatically impacts the kinds of structures observed and also that the rate of solvent removal plays a role in the orientation of the nanodomains [126,127]. Cylinder-forming diblock copolymers demonstrate better order when vapor annealed, but are more sensitive to aging effects than thermally annealed counterparts [128]. Although compressed fluids are generally poor solvents, supercritical CO 2 has recently been demonstrated as an efficient plasticizer for block copolymer annealing [129][130][131].…”

Section: Inducing Order During Film Formationmentioning

confidence: 99%

Patterning with block copolymer thin films

Segalman

2005

Materials Science and Engineering: R: Reports

935

921

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The nanometer-scale architectures in thin films of self-assembling block copolymers have inspired a variety of new applications. For example, the uniformly sized and shaped nanodomains formed in the films have been used for nanolithography, nanoparticle synthesis, and high-density information storage media. Imperative to all of these applications, however, is a high degree of control over orientation of the nanodomains relative to the surface of the film as well as control over order in the plane of the film. Induced fields including electric, shear, and surface fields have been demonstrated to influence orientation. Both heteroepitaxy and graphoepitaxy can induce positional order on the nanodomains in the plane of the film. This article will briefly review a variety of mechanisms for gaining control over block copolymer order as well as many of the applications of these materials. Particular attention is paid to the potential of perfecting long-range two-dimensional order over a broader range of length scales and the extension of these concepts to functional materials and more complex architectures. #

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Section: Inducing Order During Film Formationmentioning

confidence: 99%

Patterning with block copolymer thin films

Segalman

2005

Materials Science and Engineering: R: Reports

935

921

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“…Increasingly, research has concentrated on the evolution of microstructure and transformation between various phases in response to solvent swelling. [5][6][7][8][9][10][11] Though the preparation process usually leads to the formation of metastable structures that do not represent the melt equilibrium, such structures often exhibit high regularity and may be of particular interest for patterning applications as they significantly increase the number of patterns to be created by a given polymer.…”

Section: Introductionmentioning

confidence: 99%

Solvent Induced Sphere Development in Symmetric Diblock Copolymer Thin Films

Peng

Wei

Wang

et al. 2005

Macromol. Rapid Commun.

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Summary: We follow the time development of the microdomain structure in symmetric polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA) diblock copolymer thin films during acetone vapor treatment. Besides the highly ordered nanoscopic spheres or stripes as reported previously, a novel so‐called flower‐like pattern, which comprises six PS spheres and each PS sphere belongs to three “flowers” is formed. This finding is very helpful to discuss the highly ordered nanoscopic sphere formation process.Transition from flower‐like structure to well‐ordered arrays of spheres, in which the flower‐like pattern, the transitional morphology, and the ordered spheres are in the portion A, B, and C, respectively.imageTransition from flower‐like structure to well‐ordered arrays of spheres, in which the flower‐like pattern, the transitional morphology, and the ordered spheres are in the portion A, B, and C, respectively.

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“…The isoprene block has 92% 1,4 addition. The molecular weight ratio of PS to PI results in cylindrical morphology [16,17]. The film was processed by the "solvent annealing" procedure [17] and then was baked for 20 min in vacuum at 50 °C.…”

mentioning

confidence: 99%

“…With moderate etching (Figure 1(b)), while the lateral morphology is intact, the height difference between the crest and trough, Δh, is 6 nm, compared with 0.3 nm for the unexposed sample. Since PS is at the crest [17], the increase in Δh due to corona exposure plasma implies that PI which is at the trough is etched at a faster rate. Previous TEM study of the block copolymer has shown that diameters of the PS cylinders were ~14 nm [16].…”

mentioning

confidence: 99%

Selective assembly of nanoparticles on block copolymer by surface modification

Niu

Saraf

2007

Nanotechnology

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Block copolymers have long been recognized as scaffolds to pattern nanoparticles to construct hybrid structures for various electronic [1], optical [2,3] and optoelectronic [4] applications. Earlier studies focused on synthesizing nanoparticles selectively on the nanoscopic elements of the block copolymer [5,6] to obtain ordered structures and fabricate nanodevices, such as nanowires [7]. In other studies, the hierarchical self-assembly of nanoparticles in a nanoparticle-block copolymer mixture was demonstrated where the particles were selectively drawn towards one of the components of the ordered block copolymer morphology [8][9][10]. Based on the possibility of coupling the thermodynamic ordering of the block copolymer and the selective interaction of nanoparticles with the components of the block copolymer, spontaneous ordering of nanoparticles is theorized [11][12][13] and experimentally demonstrated [14,15]. In this paper we describe a method to selectively deposit pre-synthesized nanoparticles on a (preformed) ordered block copolymer surface using a simple approach where one of the nanoscopic polymer domains is selectively functionalized using reactive plasma.PS-PI-PS tri-block copolymer, supplied by Dexco, was deposited on a Si (silicon) substrate as a thin film by spincasting a 1% solution in toluene. Spinning speed was 3,000 rpm and spinning time was 30 s. Initial thickness of the film is 26-28 nm as confirmed by ellipsometry. Molecular weights (MW) of the two PS and central PI blocks are 18,000 Daltons each and 64,000 Daltons, respectively. The isoprene block has 92% 1,4 addition. The molecular weight ratio of PS to PI results in cylindrical morphology [16,17]. The film was processed by the "solvent annealing" procedure [17] and then was baked for 20 min in vacuum at 50 °C. Next, the film was exposed to corona discharge performed in 85% relative humidity air under ambient pressure and temperature for 3 min (moderate etching) or 4 min (deep etching), followed by a thorough rinse with DI (deionized) water. After the film was dried with air flow, it was exposed to 45 W ammonia plasma at a pressure of 580 mTorr for 10 s. Immediately after plasma treatment, the film was immersed into 10 nm Au nanoparticle solution (purchased from BBinternational) for 8-24 h. The Au nanoparticle surface is negatively charged by ClO 4 − groups (as-received). Concentration of the Au nanoparticles is 5.7 × 10 12 particles ml −1 . Prior to use, the pH of the Au nanoparticle solution was adjusted by addition of diluted HCl solution (pH = 1.5) to a value of ~5. No salt was added. Finally, the film was vigorously washed with DI water and dried in air flow.In Figure 1, tapping mode atomic force microscope (AFM) images of the film prior to corona treatment (Figure 1(a)), after corona treatment under moderate (Figure 1(b)) and deep etching (Figure 1(c)) are compared. With moderate etching (Figure 1(b)), while the lateral morphology is intact, the height difference between the crest and trough, Δh, is 6 nm, compared AbstractWe have de...

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Stability of Order in Solvent-Annealed Block Copolymer Thin Films

Cited by 58 publications

References 24 publications

Patterning with block copolymer thin films

Patterning with block copolymer thin films

Solvent Induced Sphere Development in Symmetric Diblock Copolymer Thin Films

Selective assembly of nanoparticles on block copolymer by surface modification

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