Phase behaviour of colloidal superballs mixed with non-adsorbing polymers

García, Álvaro González; Opdam, Joeri; Tuinier, Remco

doi:10.1140/epje/i2018-11719-3

Cited by 9 publications

(3 citation statements)

References 68 publications

(110 reference statements)

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“…To assess our proposed mechanism of depletion-driven gelation and better understand the influence of nanocrystal shape on the gelation threshold, we compare theoretical predictions for the phase behavior of the nanocrystal–depletant mixture to our experimental observations. Phase diagrams incorporating depletion attractions for both spherical and cubic nanocrystals are computed using free volume theory and scaled particle theory to determine the spinodal boundaries. Details of these calculations are found in the Supporting Information.…”

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confidence: 99%

Universal Gelation of Metal Oxide Nanocrystals via Depletion Attractions

et al. 2020

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Nanocrystal gelation provides a powerful framework to translate nanoscale properties into bulk materials and to engineer emergent properties through the assembled microstructure. However, many established gelation strategies rely on chemical reactions and specific interactions, e.g., stabilizing ligands or ions on the nanocrystals' surfaces, and are therefore not easily transferrable.Here, we report a general gelation strategy via non-specific and purely entropic depletion attractions applied to three types of metal oxide nanocrystals. The gelation thresholds of two compositionally distinct spherical nanocrystals agree quantitatively, demonstrating the adaptability of the approach for different chemistries. Consistent with theoretical phase behavior predictions, nanocrystal cubes form gels at a lower polymer concentration than nanocrystal spheres, allowing shape to serve as a handle to control gelation. These results suggest that the fundamental underpinnings of depletion-driven assembly, traditionally associated with larger colloidal particles, are also applicable at the nanoscale.

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confidence: 99%

Universal Gelation of Metal Oxide Nanocrystals via Depletion Attractions

et al. 2020

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“…Moreover, it has been shown that anisotropy in the particle shape can be taken into account in a relatively simple manner with FVT. [39][40][41][42] For these reasons, FVT is a promising and versatile method to gain insight into the phase behavior of colloidal mixtures. However, already for the binary hard-sphere mixture, there is a significant discrepancy between the FVT results in comparison with the results from simulations 33 and perturbation theory.…”

Section: Introductionmentioning

confidence: 99%

Phase behavior of binary hard-sphere mixtures: Free volume theory including reservoir hard-core interactions

Opdam

Schelling

Tuinier

2021

The Journal of Chemical Physics

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“…For example, faceted particles have larger overlap volumes than spherical ones, so they experience stronger depletion attractions and assemble at lower c (Figure ). The depletion phase diagram can be computed (nearly) analytically for simple geometries and is quite accurate compared to simulations and experiments with MPs. , Its construction typically involves computing the (semigrand canonical) free energy via thermodynamic integration from a hard-particle reference state with no depletant using well-established results from free volume and scaled particle theories (FVT + SPT). , Because only physical details are needed, this analysis is descriptive of the phase behavior of a broad range of systems.…”

Section: Guiding Principles For Nanocrystal Gelationmentioning

confidence: 99%

Colloidal Nanocrystal Gels from Thermodynamic Principles

et al. 2021

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Conspectus Gels assembled from solvent-dispersed nanocrystals are of interest for functional materials because they promise the opportunity to retain distinctive properties of individual nanocrystals combined with tunable, structure-dependent collective behavior. By incorporating stimuli-responsive components, these materials could also be dynamically reconfigured between structurally distinct states. However, nanocrystal gels have so far been formed mostly through irreversible aggregation, which has limited the realization of these possibilities. Meanwhile, gelation strategies for larger colloidal microparticles have been developed using reversible physical or chemical interactions. These approaches have enabled the experimental navigation of theoretically predicted phase diagrams, helping to establish an understanding of how thermodynamic behavior can guide gel formation in these materials. However, the translation of these principles to the nanoscale poses both practical and fundamental challenges. The molecules guiding assembly can no longer be safely assumed to be vanishingly small compared to the particles nor large compared to the solvent. In this Account, we discuss recent progress toward the assembly of tunable nanocrystal gels using two strategies guided by equilibrium considerations: (1) reversible chemical bonding between functionalized nanocrystals and difunctional linker molecules and (2) nonspecific, polymer-induced depletion attractions. The effective nanocrystal attractions, mediated in both approaches by a secondary molecule, compete against stabilizing repulsions to promote reversible assembly. The structure and properties of the nanocrystal gels are controlled microscopically by the design of the secondary molecule and macroscopically by its concentration. This mode of control is compelling because it largely decouples nanocrystal synthesis and functionalization from the design of interactions that drive assembly. Statistical thermodynamic theory and computer simulation have been applied to simple models that describe the bonding motifs in these assembling systems, furnish predictions for conditions under which gelation is likely to occur, and suggest strategies for tuning and disassembling the gel networks. Insights from these models have guided experimental realizations of reversible gels with optical properties in the infrared range that are sensitive to the gel structure. This process avoids time-consuming and costly trial-and-error experimental investigations to accelerate the development of nanocrystal gel assemblies. These advances highlight the need to better understand interactions between nanocrystals, how interactions give rise to gel structure, and properties that emerge. Such an understanding could suggest new approaches for creating stimuli-responsive and dissipative assembled materials whose properties are tunable on demand through directed reconfiguration of the underlying gel microstructure. It may also make nanocrystal gels amenable to computationally guided design using inve...

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Phase behaviour of colloidal superballs mixed with non-adsorbing polymers

Cited by 9 publications

References 68 publications

Universal Gelation of Metal Oxide Nanocrystals via Depletion Attractions

Universal Gelation of Metal Oxide Nanocrystals via Depletion Attractions

Phase behavior of binary hard-sphere mixtures: Free volume theory including reservoir hard-core interactions

Colloidal Nanocrystal Gels from Thermodynamic Principles

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