Three Dimensional Assembly in Directed Self-assembly of Block Copolymers

Segal‐Peretz, Tamar; Zhou, Chun; Ren, Jiaxing; Dazai, Takahiro; Ocola, Leonidas E.; Divan, Ralu; Nealey, Paul F.

doi:10.2494/photopolymer.29.653

Cited by 12 publications

(9 citation statements)

References 21 publications

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“…Vapor-phase infiltration (VPI) exposes organic polymers to vapor-phase metal-organic precursors that sorb and diffuse throughout the polymer, eventually becoming entrapped (through reaction or loss of volatility), thus creating an organic–inorganic hybrid material. − After exposure to the metal-organic precursor, a second, vapor-phase coreactant (e.g., water vapor or oxygen) is delivered to react with the precursor inside of the polymer to produce a final inorganic product that is stable in ambient atmosphere. These hybrid materials have demonstrated a variety of commercially and industrially relevant properties such as increased electrical conductivity, − solvent stability, , photoluminescence and color change, − and enhanced mechanical properties. − Additionally, VPI can be leveraged to create high-fidelity inorganic nanostructures often from sacrificial copolymer templates − and to selectively image polymer phases in polymeric mixtures or polymer morphology with electron microscopy. − Critically, VPI is capable of forming these hybrid materials across numerous length scales and without significantly modifying the original polymer’s macroscale form or microstructure. ,, As a result, VPI has been applied in a wide variety of fields, from polymer membranes for chemical separations to photovoltaics, catalysis, triboelectricity, gas sensing, and more. Several excellent reviews exist in the VPI field that explore the multitude of applications and opportunities for this process. − …”

Section: Introductionmentioning

confidence: 81%

Reaction–Diffusion Transport Model to Predict Precursor Uptake and Spatial Distribution in Vapor-Phase Infiltration Processes

et al. 2021

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Vapor-phase infiltration (VPI) has emerged as a scalable process for transforming polymer products into a variety of organic−inorganic hybrid materials with potential applications to a number of commercial industries. However, the fundamental transport kinetics of VPI are still not well understood. Most explorations to date have relied on simple Fickian diffusion models for VPI transport. However, these Fickian diffusion models often fail to entirely capture the physical phenomena of VPI because of the complex convolution of diffusion and reaction processes. In this work, a reaction−diffusion model is developed that provides additional insight into how the presence of reactions between polymers and metal-organic precursors modifies the transport behavior of the metal-organic VPI precursor through the infiltrated polymer. From this model, parameters such as the second-order rate constant for the reaction between the precursor and polymer and a diffusive hindering factor can be extracted. The model is shown to both fit well to physical measurements and, more critically, predict experimental outcomes. Additionally, nondimensionalization is employed to create domain maps based on a wide variety of VPI parameters. The resulting domain maps showcase the breadth of behaviors captured by this reaction−diffusion model for VPI.

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Section: Introductionmentioning

confidence: 81%

Reaction–Diffusion Transport Model to Predict Precursor Uptake and Spatial Distribution in Vapor-Phase Infiltration Processes

et al. 2021

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“…During VPI, metalorganic precursors sorb into the polymer surface, diffuse throughout the polymer bulk, and become entrapped either through reactions with the polymer or condensation due to reactions with coreactants. , VPI has been used to dope conductive polymers, create more sorbent foams for oil spill remediation, enhance the modulus of resilience for nanomechanical actuation, z -contrast stain copolymers to better visualize microstructural features in electron microscopy, ,− and alter the photoluminescent properties of polymeric fabrics. , …”

Section: Introductionmentioning

confidence: 99%

Increased Chemical Stability of Vapor-Phase Infiltrated AlO_x–Poly(methyl methacrylate) Hybrid Materials

Leng

Losego

2020

ACS Appl. Polym. Mater.

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Vapor-phase infiltration (VPI) transforms polymers into unique organic−inorganic hybrid materials with properties that differ from the parent polymer. Here, hybrid materials created by the infiltration of poly(methyl methacrylate) (PMMA) with trimethylaluminum (TMA) exhibit enhanced chemical stability when immersed in various solvents including toluene, cyclohexanone, and tetrahydrofuran that normally dissolve the parent PMMA. While all AlO x −PMMA hybrid materials show enhanced stability compared to the parent PMMA polymer, the VPI process temperature affects the hybrid material's structure (inorganic loading fraction and chemical bonding to the organic component), resulting in differences in chemical stability. At lower VPI process temperatures, inorganics become primarily physically entrapped or entangled with the polymer chains, leading to chemical stability that is dependent on solvent chemistry, including observed leaching of the inorganic component in aqueous solvents. In contrast, at higher VPI process temperatures, despite less inorganic loading, the inorganic is primarily chemically bound to the organic polymer, leading to hybrid structures that are completely insoluble in all explored solvents. Further, chemical stability does not require complete infiltration of the polymer. For the most stable hybrid chemistries, it is possible to infiltrate to a depth of only about 0.5 μm to make a bulk acrylic object (e.g., Plexiglas) resistant to chemical dissolution. However, process scale-up for treatment of bulk objects requires sufficient drying of the bulk acrylic prior to VPI treatment to prevent chemical vapor deposition (CVD) like growth of metal oxide on the surface due to reactions between the vapor-phase metalorganic precursor and desorbing water at the acrylic surface.

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“…We use the similar sample staining and STEM tomography methods as described in an earlier paper. 12,15 Al 2 O 3 sequential infiltration synthesis (SIS) was performed on each TEM samples using alternating exposures to trimethylaluminum and deionized H 2 O to selectively stain PMMA and provide imaging contrast and stability. STEM tomography was performed using a field-emission gun TEM (FEI Tecnai) operated at 200 kV.…”

Section: Stem Tomography and Three-dimensional Reconstructionmentioning

confidence: 99%

“…Recently, STEM tomography has been developed to probe different BCP 3-D structures and it is especially suitable for capturing heterogeneous and complicated morphologies. 12,15,23 In this study, we use an established TEM sample preparation approach based on the back-etching of SiN x -coated h100i Si wafers. 11 The template made of SOC as well as block polymer films on the front side of wafer is perfectly preserved.…”

Section: Simulationmentioning

confidence: 99%

“…Here, we developed a 3-D metrology for graphepitaxial hole shrink process using post-DSA membrane fabrication techniques and scanning transmission electron microscopy (STEM) tomography. 11,12 The self-assembly of PS-b-PMMA cylinders was directed by guide holes made of spin-on carbon (SOC) on silicon nitride-coated Si substrate, which was then made into membrane sample for TEM characterization. Two different brushes were used to modify the affinity of the sidewall and bottom surface separately.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Studying the effects of chemistry and geometry on DSA hole-shrink process in three-dimensions

Zhou

Kurosawa

Dazai

et al. 2018

J. Micro/Nanolith. MEMS MOEMS

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Acquiring three-dimensional (3-D) information becomes increasingly important for the development of block copolymer (BCP) directed self-assembly (DSA) lithography, as two-dimensional imaging is no longer sufficient to describe the 3-D nature of DSA morphology and probe hidden structures under the surface. Using the post-DSA membrane fabrication technique and scanning transmission electron microscopy tomography, we were able to characterize the 3-D structures of BCP in graphoepitaxial DSA hole shrink process. Different DSA structures of singlets formed in templated holes with different surface chemistry and geometry were successfully captured and their 3-D shapes were reconstructed from tomography data. The results reveal that strong polystyrene-preferential sidewalls are necessary to create vertical DSA cylinders and that template size outside of process window could result in defective DSA results in 3-D. Our study as well as the established 3-D metrology would greatly help to develop a fundamental understanding of the key DSA factors for optimizing the graphoepitaxial hole shrink process.

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Three Dimensional Assembly in Directed Self-assembly of Block Copolymers

Cited by 12 publications

References 21 publications

Reaction–Diffusion Transport Model to Predict Precursor Uptake and Spatial Distribution in Vapor-Phase Infiltration Processes

Reaction–Diffusion Transport Model to Predict Precursor Uptake and Spatial Distribution in Vapor-Phase Infiltration Processes

Increased Chemical Stability of Vapor-Phase Infiltrated AlO_x–Poly(methyl methacrylate) Hybrid Materials

Studying the effects of chemistry and geometry on DSA hole-shrink process in three-dimensions

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Three Dimensional Assembly in Directed Self-assembly of Block Copolymers

Cited by 12 publications

References 21 publications

Reaction–Diffusion Transport Model to Predict Precursor Uptake and Spatial Distribution in Vapor-Phase Infiltration Processes

Reaction–Diffusion Transport Model to Predict Precursor Uptake and Spatial Distribution in Vapor-Phase Infiltration Processes

Increased Chemical Stability of Vapor-Phase Infiltrated AlOx–Poly(methyl methacrylate) Hybrid Materials

Studying the effects of chemistry and geometry on DSA hole-shrink process in three-dimensions

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Product

Resources

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Increased Chemical Stability of Vapor-Phase Infiltrated AlO_x–Poly(methyl methacrylate) Hybrid Materials