Tunable and rapid self-assembly of block copolymers using mixed solvent vapors

Park, Woon Ik; Tong, Sheng; Liu, Yuzi; Jung, Il Woong; Roelofs, Andreas; Hong, Seungbum

doi:10.1039/c4nr04726e

Cited by 27 publications

(30 citation statements)

References 42 publications

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“…Block copolymers (BCPs) have gained a lot of attention due to their ability to self‐assemble into nanostructures, which may serve as templates for nanolithography, organic photovoltaics, and nanoporous films . Imperative for use in these applications is a defect‐free, controllable structure with the feature size in the nanometer range .…”

Section: Introductionmentioning

confidence: 99%

In Situ Tracking of Composition and Morphology of a Diblock Copolymer Film with GISAXS during Exchange of Solvent Vapors at Elevated Temperatures

Berezkin

Jung

Posselt

et al. 2018

Adv Funct Materials

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Solvothermal vapor annealing at elevated temperature is applied to a thin film from a cylinder-forming polystyrene-block-poly(dimethyl siloxane) (PS-b-PDMS) diblock copolymer. At this, the film is swollen in the vapor of n-heptane (highly selective for PDMS). This vapor is stepwise replaced by the vapor of toluene (weakly selective for PS). The morphologies are investigated using in situ, real-time grazing-incidence small-angle X-ray scattering (GISAXS). The initial cylindrical morphology is transformed into, among others, the lamellar one. This novel type of experiments allows probing a trajectory in the state diagram of the PS-b-PDMS/n-heptane/toluene mixture. To corroborate the morphologies, they are generated by molecular simulations, and the 2D GISAXS maps are calculated using the distorted-wave Born approximation. To relate the morphologies to the solvent distribution in the two types of nanodomains, the latter is estimated from the intensities of the Bragg reflections in the 2D GISAXS maps along with the swelling ratio of the film. Comparison with the results from a similar experiment carried out at room temperature results in the same sequence of morphologies; however, at elevated temperature, more well-ordered structures are obtained. This new approach proves to be efficient to achieve a block copolymer thin film having a desired morphology and orientation.

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Section: Introductionmentioning

confidence: 99%

In Situ Tracking of Composition and Morphology of a Diblock Copolymer Film with GISAXS during Exchange of Solvent Vapors at Elevated Temperatures

Berezkin

Jung

Posselt

et al. 2018

Adv Funct Materials

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“…Solvent annealing also offers the possibility to choose solvents selective for one of the blocks in the copolymer [19,26,[28][29][30][31][32][33][34][35][36]. A selective solvent swells one block more than the other block(s) causing an increase in the effective volume fraction of that block during the annealing process.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Chavis et al used one poly(2-hydroxyethyl methacrylate)-b-poly(methyl methacrylate) (PHEMA-b-PMMA) BCP to create four different morphologies including hexagonally ordered cylinders by using selective solvent annealing [31]. Precise control of selective solvents was also used to shift to different morphologies during annealing of polystyrene-b-poly(2-vinylpyridine) (PS-P2VP) BCPs as reported by Park et al [33] An additional interesting feature of using selective solvents is that the orientation of the cylindrical morphologies may be modified [26,36,[38][39][40]. For PS-b-P4VP BCPs, parallel cylinders were obtained using the non-selective solvent chloroform whereas cylinders oriented perpendicularly in case of using the PS block selective solvent 1,4-dioxane [38,39].…”

Section: Introductionmentioning

confidence: 99%

“…There exist several solvent annealing studies of BCPs containing pH responsive blocks, including polyacrylic acid (PAA) [46], P2VP and P4VP [28,33,38,[47][48][49][50][51], and pH and temperature dual-responsive blocks, including poly(N,N'-dimethylaminoethylmethacrylate) (PDMAEMA) and poly(N,N'-diethylaminoethylmethacrylate) (PDEAEMA) [52]. One of the most widely used thermo-responsive blocks in BCPs is poly(N-isopropylacrylamide) (PNIPAM) which has a lower critical solution temperature (LCST) at 32 °C.…”

Section: Introductionmentioning

confidence: 99%

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Self-assembly of PS-b-PNIPAM-b-PS block copolymer thin films via selective solvent annealing

Cetintas

Kamperman

2016

Polymer

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Block copolymer (BCP) thin films are interesting material systems for nanofabrication since they can form well-defined periodic nanostructures by microphase separation. However, attaining a specific morphology with the required orientation can be challenging. In this study, we investigated the morphological behavior of polystyrene-b-poly(N-isopropylacrylamide)-bpolystyrene (PS-b-PNIPAM-b-PS) BCP thin films by using Atomic Force Microscopy (AFM) and in-situ Grazing-Incidence X-ray Scattering (GISAXS) during selective solvent annealing. Thin films of a lamellar BCP were annealed by using various solvents with different selectivity for the blocks, such as PNIPAM-selective methanol, non-selective tetrahydrofuran (THF) and PS-selective toluene. Solvent annealing using methanol: THF 1:2 (v:v) or methanol: toluene 1:1 (v:v) resulted in the formation of hexagonally ordered perpendicular cylinders, whereas no sustained long-range order was found when only one type of solvent was used. PS-b-PNIPAM-b-PS BCP thin films that have hexagonally ordered perpendicular cylinders are promising for applications where thermo-responsiveness is desired, such as nanofiltration and biomedical applications.

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“…Combining a nonselective with a selective solvent or two solvents being selective for either block and varying the mixing ratio may overcome these limitations and pave the way for a systematic variation of the degree of swelling of the different microdomains. Very detailed studies of the influence of the properties of solvent mixtures on the thin film structures have been reported; however, so far mostly ex-situ investigations have been carried out[92,211,[213][214][215][216][217][218][219].…”

mentioning

confidence: 99%

Restructuring in block copolymer thin films: In situ GISAXS investigations during solvent vapor annealing

Posselt

Zhang

Smilgies

et al. 2017

Progress in Polymer Science

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Block copolymer (BCP) thin films have been proposed for a number of nanotechnology applications, such as nanolithography and as nanotemplates, nanoporous membranes and sensors. Solvent vapor annealing (SVA) has emerged as a powerful technique for manipulating and controlling the structure of BCP thin films, e.g.,, by healing defects, by altering the orientation of the microdomains and by changing the morphology. Due to high time resolution and compatibility with SVA environments, grazing-incidence small-angle X-ray scattering (GISAXS) is an indispensable technique for studying the SVA process, providing information of the BCP thin film structure both laterally and along the film normal. Especially, state-of-the-art combined GISAXS/SVA setups at synchrotron sources have facilitated in-situ and real-time studies of the SVA process with a time resolution of a few seconds, giving important insight into the pathways and mechanisms of SVA induced restructuring. We give a short introduction to the GISAXS method and review recent theoretical studies, experimental techniques such as sample preparation and in-situ chambers together with SVA protocols, and we review and discuss experimental results. We conclude by giving an outlook on emerging developments of the in-situ real-time GISAXS scattering technique in combination with new approaches to control BCP thin film structures using SVA.

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Tunable and rapid self-assembly of block copolymers using mixed solvent vapors

Cited by 27 publications

References 42 publications

In Situ Tracking of Composition and Morphology of a Diblock Copolymer Film with GISAXS during Exchange of Solvent Vapors at Elevated Temperatures

In Situ Tracking of Composition and Morphology of a Diblock Copolymer Film with GISAXS during Exchange of Solvent Vapors at Elevated Temperatures

Self-assembly of PS-b-PNIPAM-b-PS block copolymer thin films via selective solvent annealing

Restructuring in block copolymer thin films: In situ GISAXS investigations during solvent vapor annealing

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