Scattering Study on the Selective Solvent Swelling Induced Surface Reconstruction

Xu, Ting; Goldbach, James T.; Misner, Matthew J.; Kim, Seung Hyun; Gibaud, Alain; Gang, Oleg; Ocko, B. M.; Guarini, K.W.; Black, Charles T.; Hawker, Craig J.; Russell, Thomas P.

doi:10.1021/ma0355204

Cited by 78 publications

(73 citation statements)

References 25 publications

(47 reference statements)

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“…Selective solvents have been used for reversible self-assembly or reconstruction/reorganization of polymer domains in block copolymers 23,24 . Cyclohexane has been recognized as one such solvent for selective removal of PS in PMMA matrix 25 .…”

Section: Resultsmentioning

confidence: 99%

Graphene Nanomesh As Highly Sensitive Chemiresistor Gas Sensor

et al. 2012

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Graphene is a one atom thick carbon allotrope with all surface atoms that has attracted significant attention as a promising material as the conduction channel of a field-effect transistor and chemical field-effect transistor sensors. However, the zero bandgap of semimetal graphene still limits its application for these devices. In this work, ethanol-chemical vapor deposition (CVD) grown p-type semiconducting large-area monolayer graphene film was patterned into nanomesh by the combination of nanosphere lithography and reactive ion etching and evaluated as field-effect transistor and chemiresistor gas sensors. The resulting neck-width of the synthesized nanomesh was about ~20 nm comprised of the gap between polystyrene spheres that was formed during the reactive ion etching process. The neck-width and the periodicities of the graphene nanomesh could be easily controlled depending the duration/power of RIE and the size of PS nanospheres. The fabricated GNM transistor device exhibited promising electronic properties featuring high drive current and ION/IOFF ratio of about 6, significantly higher than its film counterpart. Similarly, when applied as chemiresistor gas sensor at room temperature, the graphene nanomesh sensor showed excellent sensitivity towards NO2 and NH3, significantly higher than their film counterparts. The ethanol-based graphene nanomesh sensors exhibited sensitivities of about 4.32%/ppm in NO2 and 0.71%/ppm in NH3 with limit of detections of 15 ppb and 160 ppb, respectively. Our demonstrated studies on controlling the neck width of the nanomesh would lead to further improvement of graphene-based transistors and sensors.

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Section: Resultsmentioning

confidence: 99%

Graphene Nanomesh As Highly Sensitive Chemiresistor Gas Sensor

et al. 2012

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“…However, they found during the course of acetic acid treatment, some PMMA chains from the block copolymer migrated to the underlying PS/ PMMA random copolymer brush layer (this random copolymer brush was grafted on to the substrate to balance the interfacial energy for the purpose of inducing the perpendicular orientation of PMMA domains), increasing the brush layer thickness by ≈ 1 nm. [ 52 ] Due to to the ultrathin nature of the polymer layer that cushions the pores, typically only a few nanometers, electron tunneling takes place [ 51 ] and makes it possible to carry out electrochemical reactions across the ultrathin polymer layer under the porous fi lm templates supported on conductive substrates to grow various types of nanomaterials. [ 50 ] [ 47 ,52-54 ] in the weak aggregation limit, were reported to undergo a swelling-induced pore-forming morphology reconstruction under appropriate swelling conditions.…”

Section: Morphology Tuning Of the Poresmentioning

confidence: 99%

An Emerging Pore‐Making Strategy: Confined Swelling‐Induced Pore Generation in Block Copolymer Materials

2011

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Block copolymers (BCPs) composed of two or more thermodynamically incompatible homopolymers self-assemble into periodic microdomains. Exposing self-assembled BCPs with solvents selective to one block causes a swelling of the domains composed of this block. Strong swelling in the confinement imposed by the matrix of the other glassy block leads to well-defined porous structures via morphology reconstruction. This confined swelling-induced pore-making process has emerged recently as a new strategy to produce porous materials due to synergic advantages that include extreme simplicity, high pore regularity, involvement of no chemical reactions, no weight loss, reversibility of the pore forming process, etc. The mechanism, kinetics, morphology, and governing parameters of the confined swelling-induced pore-making process in BCP thin films are discussed, and the main applications of nanoporous thin films in the fields of template synthesis, surface patterning, and guidance for the areal arrangements of nanomaterials and biomolecules are summarized. Recent, promising results of extending this mechanism to produce BCP nanofibers or nanotubes and bulk materials with well-defined porosity, which makes this strategy also attractive to researchers outside the nanocommunity, are also presented.

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“…Using freeze-drying, they were able to successfully freeze-in microstructures of solution-cast films at different times under extremely slow evaporation rates, which corresponded to frozen-in phase structures at qualitatively different block copolymer concentrations, ϕ. Thirdly, solvent vapor annealing after the polymer film has been prepared can lead to well-ordered film structures. [14][15][16][17][18][19][20][21][22][23][24][25] In Russell and coworker's work, [1,[26][27][28][29][30][31][32] films of PS-b-PMMA, polystyrene-b-poly(ethylene oxide) (PS-b-PEO), PS-b-PEO/PEO blends, and PS-b-PEO/PMMA blends were annealed by different vapors, and highly ordered microdomains with long-range lateral order in large areas without any defects were obtained.…”

Section: Ordered Structure Induced By Solventmentioning

confidence: 99%

Solvent-Induced Crystallization of PS-b-PEO-b-PS Block Copolymer Films

Luo

Han

Gao

et al. 2010

Journal of Macromolecular Science, Part B

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Solvent-induced crystallization and dewetting behaviors of polystyrene-b-poly (ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) block copolymer films deposited on three different substrates, silicon, mica, and carbon-coated mica have been studied by atomic force microscope (AFM). When the common solvent dichloromethane was used for annealing, the films on all three of the substrates exhibited dewetting behavior; the dendritic crystallization patterns were found in the dewetted regions for the films on silicon and mica substrates, while for the films on carbon-coated mica, no crystallization pattern appeared. According to the observation of the crystallization patterns formed in the films with different initial thicknesses, it is shown that the width of the dendritic branches decreases with the increase of film thickness and solvent annealing time. When the PS-selective solvent toluene was used for annealing, the dewetting process was absent, and the crystallization patterns were observed on the surface of the films on all three kinds of substrates.

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Scattering Study on the Selective Solvent Swelling Induced Surface Reconstruction

Cited by 78 publications

References 25 publications

Graphene Nanomesh As Highly Sensitive Chemiresistor Gas Sensor

Graphene Nanomesh As Highly Sensitive Chemiresistor Gas Sensor

An Emerging Pore‐Making Strategy: Confined Swelling‐Induced Pore Generation in Block Copolymer Materials

Solvent-Induced Crystallization of PS-b-PEO-b-PS Block Copolymer Films

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