Kinetics of Nonequilibrium Nanocrystal Monolayer Formation:  Deposition from Liquid Carbon Dioxide

Shah, Parag S.; Novick, Brian J.; Hwang, Ha Soo; Lim, Kwon Taek; Carbonell, Ruben G.; Johnston, Keith P.; Korgel, Brian A.

doi:10.1021/nl034793+

Cited by 39 publications

(66 citation statements)

References 26 publications

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“…The Gibbs energy cost of forming a hole of radius R in a nonvolatile (nv) film of thickness t is

Δ G_{hole, nv} = 2 π R γ t + π R^{2} (S - \frac{A}{t^{2}})

…”

Section: Discussionmentioning

confidence: 99%

“…In addition to disjoining pressure effects for hole formation, solvent evaporation accounted for thin‐film instabilities and dewetting for volatile thin liquid films . Of two mechanisms envisaged for the formation of holes due to solvent evaporation, the first possibility is residual stress from nonequilibrium chain conformations due to quick drying .…”

Section: Discussionmentioning

confidence: 99%

“…The second possibility and preferred mechanism is that a quick removal of volatile solvents from a film created a large chemical potential difference that invariably favored film instabilities and dewetting . The Gibbs energy barrier for nucleation to form holes with radius R in a thin volatile (v) film of thickness t is given by

Δ G_{hole, v} = - \frac{π R^{2} t}{Ω} Δ μ + 2 π R γ t + π R^{2} (S - \frac{A}{t^{2}})

w i t h Δ μ = k_{normalB} T \ln (p^{vap} / p^{normali})

in which Ω denotes the molecular volume, k B denotes the Boltzmann constant, p vap denotes the solvent vapor pressure, and p i denotes the partial pressure in the vapor phase.…”

Section: Discussionmentioning

confidence: 99%

“…In our case, P(S‐ b ‐4VP) thin films wetted PS–SiO x /Si only partially because S < 0 and A > 0. Like hexane and trichloromethane, THF is a volatile solvent. Δ μ for the evaporation of THF solvent at 25 °C is large because P vap / P i ≈ 1 × 10 5 .…”

Section: Discussionmentioning

confidence: 99%

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Film Instability of Amphiphilic Block Copolymer Thin Films Driven by Solvent Annealing and Drying

Sun

Chen

Liou

et al. 2015

Macro Chemistry & Physics

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This paper investigates the film instability and structural evolution of solvent‐annealed polystyrene‐block‐poly(4‐vinylpyridine), P(S‐b‐4VP), as thin films of initially monolayer thickness on bare substrates (SiOx/Si) and substrates coated with end‐grafting PS (PS–SiOx/Si) under tetrahydrofuran vapor. At an early stage of solvent annealing, merging of nanospheres to form nanocylinders produces film rupture, creating small holes within a continuous layer. Because of the connectivity, the coalescence of incipient holes is driven by 2D pressure relaxation. Upon further iterative solvent annealing and drying, flat islands progressively grow outward at the expense of expanding holes until they contact with the edges of holes to form a network‐like cellular structure, and then decay into hemispherical droplets. The capillary driving forces associated with the negative excess interfacial entropy are responsible for the film instability of micelles on PS–SiOx/Si. In contrast, thin P(S‐b‐4VP) films on SiOx/Si reveal only small holes during iterative swelling and drying. The presence of these small holes is ascribed to an incomplete coverage during the merging of nanospheres and the anchoring of P(S‐b‐4VP) chains on SiOx/Si. Adsorption in micellar films has three important effects—retarding the motion of micelles, increasing the film stability, and favoring complete wetting.

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“…The Gibbs energy cost of forming a hole of radius R in a nonvolatile (nv) film of thickness t is

Δ G_{hole, nv} = 2 π R γ t + π R^{2} (S - \frac{A}{t^{2}})

…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Δ G_{hole, v} = - \frac{π R^{2} t}{Ω} Δ μ + 2 π R γ t + π R^{2} (S - \frac{A}{t^{2}})

w i t h Δ μ = k_{normalB} T \ln (p^{vap} / p^{normali})

in which Ω denotes the molecular volume, k B denotes the Boltzmann constant, p vap denotes the solvent vapor pressure, and p i denotes the partial pressure in the vapor phase.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Film Instability of Amphiphilic Block Copolymer Thin Films Driven by Solvent Annealing and Drying

Sun

Chen

Liou

et al. 2015

Macro Chemistry & Physics

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“…Shah et al have stabilized silver (Ag) nanocrystals in scCO 2 with perfluorodecanethiol ligand [16]. The perfluoropolyether-based ligands were also found to be effective in dispersing nanocrystals in scCO 2 [19,20].…”

Section: Introductionmentioning

confidence: 99%

Solvation structure and dynamics for passivated Au nanoparticle in supercritical CO2: A molecular dynamic simulation

et al. 2011

Journal of Colloid and Interface Science

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Supercritical Fluids

Tomasko¹,

Guo²

2006

Kirk-Othmer Encyclopedia of Chemical Technology

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A supercritical fluid is characterized as a gas that is pressurized and heated to a compressed fluid state, which is above both the critical pressure and temperature. In this state, density and subsequently solvent strength and transport properties are highly adjustable by modest changes in temperature and pressure. Complex phase behavior and interactions with materials can occur. This behavior can be examined experimentally and described successfully by molecular thermodynamics. Carbon dioxide and water are two substances used frequently as supercritical fluids. The former, which may be used independently or in the presence of various cosolvents, is predominantly used because of its environmentally benign nature and low cost. The latter is used because of its efficiency in destroying hazardous aqueous pollutants and hydrothermal synthesis. Numerous supercritical fluid processes have been commercialized, including coffee and tea decaffeination, supercritical water oxidation, and supercritical fluid chromatography. Process research and development involving supercritical fluids are progressing in many diverse areas, including extraction, membrane filtration, polymerization, particle formation, cleaning and drying, and applications in microelectronic engineering.

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Kinetics of Nonequilibrium Nanocrystal Monolayer Formation: Deposition from Liquid Carbon Dioxide

Cited by 39 publications

References 26 publications

Film Instability of Amphiphilic Block Copolymer Thin Films Driven by Solvent Annealing and Drying

Film Instability of Amphiphilic Block Copolymer Thin Films Driven by Solvent Annealing and Drying

Solvation structure and dynamics for passivated Au nanoparticle in supercritical CO2: A molecular dynamic simulation

Supercritical Fluids

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