Multiple dynamic regimes in colloid‐polymer dispersions: New insight using X‐ray photon correlation spectroscopy

Srivastava, Sunita; Kishore, Suhasini; Narayanan, Suresh; Sandy, Alec; Bhatia, Surita R.

doi:10.1002/polb.23973

Cited by 13 publications

(22 citation statements)

References 65 publications

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“…Recent work has used photon correlation imaging paired with dynamic light scattering, 117,118 and X-ray photon correlation spectroscopy 72,119 to investigate structural evolution with time towards assembly, as well as the homogeneity (or heterogeneity) of the structures.…”

Section: Discussionmentioning

confidence: 99%

“…We find that depletion attractions are effective for driving assembly of polymer-wrapped NCs. Moreover, through variations in the PEO surface polymer graft density and MW, we demonstrate that the polymer shell structure significantly modifies the depletion attraction-in ways analogous to behavior of grafted nanoparticle-polymer composites 68,71,72 -with implications for phase behavior, rheology, and optical properties. Perhaps the most striking consequence is the emergence of a depletant MW threshold for assembly that depends on the architecture of the polymer wrapping.…”

Section: Introductionmentioning

confidence: 91%

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Depletion-driven assembly of polymer-coated nanocrystals

Green

Kadulkar

Sherman

et al. 2022

Preprint

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Depletion-driven assembly has been widely studied for micron-sized colloids, but questions remain at the nanoscale where the governing physics are impacted by the stabilizing surface ligands or wrapping polymers, whose length scales are on the same order as those of the colloidal core and the depletant. Here, we probe how wrapping colloidal tin-doped indium oxide nanocrystals with polymers affects their depletion-induced interactions and assembly in solutions of polyethylene glycol. Copolymers of polyacrylic acid grafted with polyethylene oxide provide nanocrystal wrappings with different effective polymer graft densities and molecular weights. (Ultra) small angle X-ray scattering, coarse-grained molecular dynamics simulation, and molecular thermodynamic theory were combined to analyze how depletant size and polymer wrapping characteristics affect depletion interactions, structure, and phase behavior. The results show how depletant molecular weight, as well as surface density and molecular weight of polymer grafts, set thresholds for assembly. These signatures are unique to depletion-driven assembly of nanoscale colloids and mirror phase behaviors of grafted nanoparticle--polymer composites. Optical and rheological responses of depletion-driven assemblies of nanocrystals with different polymer shell architectures were probed to learn how their structural differences impact properties. We discuss how these handles for depletion-driven assembly at the nanoscale may provide fresh opportunities for designing responsive depletion interactions and dynamically reconfigurable materials.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

Depletion-driven assembly of polymer-coated nanocrystals

Green

Kadulkar

Sherman

et al. 2022

Preprint

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“…XPCS is a technique for investigating the dynamics of nanoparticles . This technique requires partially coherent X‐rays.…”

Section: X‐ray Photon Correlation Spectroscopymentioning

confidence: 99%

Recent developments in polymer applications of synchrotron small‐angle X‐ray scattering

Sakurai

2016

Polymer International

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Synchrotron radiation facilities have been established and become very familiar in the polymer community not only from academic but also industrial viewpoints. It is not so unusual now to conduct simultaneous measurements of small-angle X-ray scattering (SAXS) with other techniques such as wide-angle X-ray scattering, stress-strain, light scattering, and so forth. New techniques have also been established and have become more familiar in recent years. In this review, recent developments in polymer applications of synchrotron SAXS are summarized. Instrumental developments and progress in data analyses are reviewed from the following aspects: ultra-small-angle X-ray scattering, anomalous SAXS, X-ray photon correlation spectroscopy, new types of simultaneous measurements, grazing-incidence SAXS, new trends in nanoparticle analyses and industrial applications.

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“…As the concentration of polymer increases in the bulk medium, polymer-particle and polymer-polymer interactions begin to play a more important role in altering the mechanisms of structural arrest. Additionally in another study, we used x-ray photon correlation spectroscopy (XPCS) to understand the dynamics in these systems at the same aging period [43]. Suspensions with 2% laponite ® and various concentrations of PEO close to the polymer overlap region and the onset into this regime was found to shift to lower concentrations with increasing polymer molecular weight.…”

Section: Scattering Of Laponite ® With Low-m W Peomentioning

confidence: 99%

Microstructure of colloid-polymer mixtures containing charged colloidal disks and weakly-adsorbing polymers

Kishore

Srivastava

Bhatia

2016

Polymer

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Structural arrest in an aging colloid-polymer mixture of charged colloidal disks and weakly interacting polymers is primarily governed by the spatial arrangement of microstructural domains in the system. Here we present a detailed ultra-small angle x-ray scattering (USAXS) study of the polymer induced microstructural changes occurring in systems containing laponite ® and poly(ethylene oxide) (PEO). Laponite ® suspensions are known to transition from a homogeneous fluid to an arrested phase as a function of time. USAXS results show that when polymer chains are added to this colloidal system, the microstructural changes are found to depend on (i) polymer-colloid size ratio, (ii) particle and polymer concentration. Large length scale structures (300-1000 nm) of non-uniformly varying size appear with increasing concentration of high molecular weight PEO (R g /R ~ 2.4). However with shorter PEO chains (R g /R ~ 0.5), we observe the formation of intermediary structures with a characteristic length scale of 50-60 nm. With increasing particle concentration, we observe a more compact structure for the high molecular weight PEO and no signature of a percolating network in the case of the low molecular PEO. We believe that these results add to our understanding of the complex aging behavior of clay-polymer systems.

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Multiple dynamic regimes in colloid‐polymer dispersions: New insight using X‐ray photon correlation spectroscopy

Cited by 13 publications

References 65 publications

Depletion-driven assembly of polymer-coated nanocrystals

Depletion-driven assembly of polymer-coated nanocrystals

Recent developments in polymer applications of synchrotron small‐angle X‐ray scattering

Microstructure of colloid-polymer mixtures containing charged colloidal disks and weakly-adsorbing polymers

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