The effect of particle-scale dynamics on the macroscopic properties of disk-shaped colloid–polymer systems

Kishore, Suhasini; Chen, Yingzhu; Ravindra, P. S.; Bhatia, Surita R.

doi:10.1016/j.colsurfa.2015.06.056

Cited by 13 publications

(17 citation statements)

References 53 publications

(58 reference statements)

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“…As polymer concentration increases, interactions between adsorbed layers and free chains can result in re-stabilization of clusters and, above the overlap concentration, cluster-cluster attractions increase so becoming long ranged. All these structural effects have been postulated for Laponite dispersions containing poly(ethylene oxide) (PEO) which can be considered a paradigmatic example of platelet dispersions in neutral polymer solutions, from dilute to concentrated regime (Baghdadi, Sardinha, & Bhatia, 2005;Baghdadi, Jensen, Easwar, & Bhatia, 2008;Kishore, Chen, Ravindra, & Bhatia, 2015;Mongondry, Nicolai, & Tassin, 2004;Zulian, Ruzicka, & Ruocco, 2008;Zulian, Augusto De Melo Marques, Emilitri, Ruocco, & Ruzicka, 2014).…”

Section: Introductionmentioning

confidence: 99%

Rheology of Laponite-scleroglucan hydrogels

Lapasin

Abrami

Grassi

et al. 2017

Carbohydrate Polymers

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a b s t r a c tBoth Laponite and scleroglucan can find several applications in various fields (from industrial to biomedical one) in virtue of their peculiar features and rheological properties displayed in aqueous phases. Structural states of Laponite dispersions strongly depend on concentration and ionic strength. When attractive and repulsive interparticle interactions are so effective that they lead to arrested states (attractive gel or repulsive glass), the rheological behavior of the dispersion undergoes a sharp transition, from quasi-Newtonian to markedly shear thinning and viscoelastic. Conversely, scleroglucan solutions gradually change to weak gels with increasing polymer concentration. The present work is concerned with aqueous Laponite-scleroglucan mixed systems, obtained according to different preparation modes, and is aimed at examining how much the content and proportion of both components affect the viscoelastic and flow properties of the mixed system.

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Section: Introductionmentioning

confidence: 99%

Rheology of Laponite-scleroglucan hydrogels

Lapasin

Abrami

Grassi

et al. 2017

Carbohydrate Polymers

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“…However, we find the RR–AR transition for S M55_L2 occurs at C P = 0.5%, which is smaller than the theoretical C sat . Recent experiments using dynamic light scattering and ultrasound attenuation spectroscopy techniques have shown that the distribution of laponite ® particles in suspensions in the early time periods is bimodal, and not monodisperse as one would expect. This was attributed to the fact that there may be partially exfoliated weak aggregates/clusters of particles or stacks of two or more laponite ® particles present in the system.…”

Section: Resultsmentioning

confidence: 96%

“…It is known that the addition of polymers to a colloidal dispersion induces an attractive interaction and can lead to re‐entrant behavior and glass–glass transitions . Though most experimental and theoretical observations have been derived from systems containing hard‐sphere colloids and nonadsorbing polymers, it was recently shown that a similar phenomenon is also seen in laponite ® dispersions with weakly adsorbing polymers, such as poly(ethylene oxide) (PEO) …”

Section: Introductionmentioning

confidence: 99%

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

Srivastava

Kishore

Narayanan

et al. 2015

J. Polym. Sci. Part B: Polym. Phys.

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We present an X-ray photon correlation spectroscopy (XPCS) study of dynamic transitions in an anisotropic colloid-polymer dispersion with multiple arrested states. The results provide insight into the mechanism for formation of repulsive glasses, attractive glasses, and networked gels of colloids with weakly adsorbing polymer chains. In the presence of adsorbing polymer chains, we observe three distinct regimes: a state with slow dynamics consisting of finite particles and clusters, for which interparticle interactions are predominantly repulsive; a second dynamic regime occurring above the saturation concentration of added polymer, in which small clusters of nanoparticles form via a short-range depletion attraction; and a third regime above the overlap concentration in which dynamics of clusters are independent of polymer chain length. The observed complex dynamic state diagram is primarily governed by the structural reorganization of a nanoparticle cluster and polymer chains at the nanoparticle-polymer surface and in the concentrated medium, which in turn controls the dynamics of the dispersion.

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“…The addition of a lower molecular weight PEO changes the macroscopic properties of the laponite system in a different manner. In a recently published work from our group, we examined the rheological behavior of mixtures containing 2% laponite and PEO of molecular weights varying between 4.6 kg/mol to 35 kg/mol [30]. In addition to the typical re-entrant behavior observed when the polymer is dilute, we also see another onset of re-stabilization very close to the polymer overlap regime.…”

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

confidence: 93%

“…Studies have also shown that by changing the concentration of small PEO chains, the system transitions through a re-entrant behavior because of increasing depletion attractions in the system. More recently our group has recently studied the effects of varying the concentration of PEO on the macroscopic properties of the system [29,30].…”

Section: Introductionmentioning

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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The effect of particle-scale dynamics on the macroscopic properties of disk-shaped colloid–polymer systems

Cited by 13 publications

References 53 publications

Rheology of Laponite-scleroglucan hydrogels

Rheology of Laponite-scleroglucan hydrogels

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

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

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