Controlled Ordering of Block Copolymer Gyroid Thin Films by Solvent Annealing

She, Ming-Shiuan; Lo, Ting-Ya; Ho, Rong‐Ming

doi:10.1021/ma402187j

Cited by 43 publications

(59 citation statements)

References 50 publications

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“…Note that the final morphology of the PS−PLLA thin film is very sensitive to the film thickness. 32 As a result, a thin film with thickness of 200 nm was prepared to satisfy the criteria of commensuration. As shown in Figure S2 (SI), the as-cast film appears with poorly ordered structures, resulting from extremely fast evaporation rate of solvent during spin coating.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The evaporation process will accompany a significant reduction in chain mobility and the morphological evolution will be suppressed when the polymer mixture reaches vitrified state. 32 As a result, the thinning process from solvent evaporation will be halted once the sample thickness reaches two times the initial thickness of the cast film.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

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Morphological Evolution of Gyroid-Forming Block Copolymer Thin Films with Varying Solvent Evaporation Rate

She

et al. 2015

ACS Appl. Mater. Interfaces

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In this study, we aim to examine the morphological evolution of block copolymer (BCP) nanostructured thin films through solvent evaporation at different rates for solvent swollen polystyrene-block-poly(l-lactide) (PS-PLLA). Interesting phase transitions from disorder to perpendicular cylinder and then gyroid can be found while using a partially selective solvent for PS to swell PS-PLLA thin film followed by solvent evaporation. During the transitions, gyroid-forming BCP thin film with characteristic crystallographic planes of (111)G, (110)G, and (211)G parallel to air surface can be observed, and will gradually transform into coexisting (110)G and (211)G planes, and finally transforms to (211)G plane due to the preferential segregation of constituted block to the surface (i.e., the thermodynamic origin for self-assembly) that affects the relative amount of each component at the air surface. With the decrease on the evaporation rate, the disorder phase will transform to parallel cylinder and then directly to (211)G without transition to perpendicular cylinder phase. Most importantly, the morphological evolution of PS-PLLA thin films is strongly dependent upon the solvent removal rate only in the initial stage of the evaporation process due to the anisotropy of cylinder structure. Once the morphology is transformed back to the isotropic gyroid structure after long evaporation, the morphological evolution will only relate to the variation of the surface composition. Similar phase transitions at the substrate can also be obtained by controlling the ratio of PLLA-OH to PS-OH homopolymers to functionalize the substrate. As a result, the fabrication of well-defined nanostructured thin films with controlled orientation can be achieved by simple swelling and deswelling with controlled evaporation rate.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

Morphological Evolution of Gyroid-Forming Block Copolymer Thin Films with Varying Solvent Evaporation Rate

She

et al. 2015

ACS Appl. Mater. Interfaces

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“…38,39 Block co-polymer molecular weight and polymeric volume fractions were found to directly affect the resultant template pore size and uniformity in the case of the hexagonal cylinder pore morphology 42,47 ; increasing the polymer block molecular weight yielded larger pores with improved homogeneity in pore size. Thus, the formulation or selection of the parent PS-b-PLLA polymer offers an opportunity for tuning the pore morphology and homogeneity in the resultant porous template.…”

Section: Synthesis Of Nanoporous Polymeric Templates From Bcpsmentioning

confidence: 99%

“…38,42,[47][48][49]68 Lines in the figure represent a range of pore sizes or sample sizes. stability.…”

Section: Template-based Fabrication Of Nanoporous Metalsmentioning

confidence: 99%

“…Using soft templates formed via block co-polymer self-assembly BCP self-assembly can be exploited to form the sacrificial soft template structure. 1,38,39 BCPs are particularly apt to be used for templating purposes due to their tendency to microphase separate into spatially uniform, homogeneously sized nanoscale domains. 40 Use of well-known BCP systems allows for templates of varying morphologies (e. g., hexagonal-cylinder, double gyroid) to be easily produced based upon the thermodynamic understanding of the parent polymer system.…”

Section: B Soft Templatesmentioning

confidence: 99%

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Template-based fabrication of nanoporous metals

Rebbecchi

Chen

2017

J. Mater. Res.

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Nanoporous metallic foams with high surface area and novel functional behavior are positioned to stimulate new multifunctional and metamaterial applications. However, there are fundamental challenges in achieving uniform nanopores and tailorable morphology. Emerging templating methods offer a wide range of applicable metallic species while enhancing control of pore morphology, uniformity, and interconnectivity. Here, a critical review of nanoporous metal fabrication is presented, with focus on templating methods utilizing nanoporous polymeric templates. Metals are introduced into percolative nanochannels of sacrificial templates by deposition, and subsequent removal of templates yields ordered nanoporous metals. We introduce approaches for preparing nanoporous templates, including utilizing block copolymer self-assembly that yields periodic gyroid networks. While metallization of templates by electrodeposition has been demonstrated, electroless deposition permits uniform deposition by many metallic species and infiltration of narrow pores. Examples of nanoporous metals with uniform pore sizes below 50 nm fabricated by templating methods are examined.

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Widely Tunable Morphologies in Block Copolymer Thin Films Through Solvent Vapor Annealing Using Mixtures of Selective Solvents

Chavis

Smilgies

Wiesner

et al. 2015

Adv Funct Materials

120

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Thin films of block copolymers are extremely attractive for nanofabrication because of their ability to form uniform and periodic nanoscale structures by microphase separation. One shortcoming of this approach is that to date the design of a desired equilibrium structure requires synthesis of a block copolymer de novo within the corresponding volume ratio of the blocks. In this work, we investigated solvent vapor annealing in supported thin films of poly(2-hydroxyethyl methacrylate)-block-poly(methyl methacrylate) [PHEMA-b-PMMA] by means of grazing incidence small angle X–ray scattering (GISAXS). A spin-coated thin film of lamellar block copolymer was solvent vapor annealed to induce microphase separation and improve the long-range order of the self-assembled pattern. Annealing in a mixture of solvent vapors using a controlled volume ratio of solvents (methanol, MeOH, and tetrahydrofuran, THF), which are chosen to be preferential for each block, enabled selective formation of ordered lamellae, gyroid, hexagonal or spherical morphologies from a single block copolymer with a fixed volume fraction. The selected microstructure was then kinetically trapped in the dry film by rapid drying. To our knowledge, this paper describes the first reported case where in-situ methods are used to study the transition of block copolymer films from one initial disordered morphology to four different ordered morphologies, covering much of the theoretical diblock copolymer phase diagram.

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Controlled Ordering of Block Copolymer Gyroid Thin Films by Solvent Annealing

Cited by 43 publications

References 50 publications

Morphological Evolution of Gyroid-Forming Block Copolymer Thin Films with Varying Solvent Evaporation Rate

Morphological Evolution of Gyroid-Forming Block Copolymer Thin Films with Varying Solvent Evaporation Rate

Template-based fabrication of nanoporous metals

Widely Tunable Morphologies in Block Copolymer Thin Films Through Solvent Vapor Annealing Using Mixtures of Selective Solvents

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