Reduced colloidal repulsion imparted by adsorbed polymer of particle dimensions

Wen, Yu; Lin, Po Chang; Lee, Chun Yi; Hua, Chi C.; Lee, Tai Chou

doi:10.1016/j.jcis.2010.05.071

Cited by 9 publications

(14 citation statements)

References 62 publications

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“…The decreasing d avg results from the reduced repulsions between GOs with adding polymers. 41,43,44 Therefore, it is not new that d avg decreases with c p in all MWs. However, it is worth noting that the d avg is decreased more with higher PEG MW at a same c p in the range of c p ≤ 10 wt.…”

Section: Resultsmentioning

confidence: 98%

Tailored Colloidal Stability and Rheological Properties of Graphene Oxide Liquid Crystals with Polymer-Induced Depletion Attractions

et al. 2018

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Graphene oxide liquid crystallinity (GO LC) has been widely exploited for high-performance graphenebased applications. In this regard, colloidal stability of GO LC suspension is a crucial requirement, particularly while polymers are often added to the GO LC. Unfortunately, current level of knowledge on how polymers influence the structure and properties of GO LC is not sufficient to systematically guide the development of applications. Here, we investigate the microstructure and rheological properties of GO LC suspensions in the presence of polymer additives with varying molecular weights and concentrations. Similar to conventional colloidal systems, nonnegligible polymer-induced interactions are found in GO LC suspensions, which can effectively modulate the interaction among GO platelets and the relevant physical properties. On the basis of extensive small-angle X-ray scattering and rheological measurements, we demonstrate that, contrary to the general perception, polymer-induced depletion attraction can increase the colloidal stability of GO, while also preventing the vitrification of GO LC. In addition, a proper level of polymer additive can reduce the viscosity of GO LC suspensions by orders of magnitude, providing an effective route to GO LC-based solution processing. After all, the colloidal stability and rheological properties of GO can significantly impact the quality of GO. Therefore, we believe that our finding will be of great interest in the field of graphene-based applications, as it presents effective strategies for improving properties.

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Section: Resultsmentioning

confidence: 98%

Tailored Colloidal Stability and Rheological Properties of Graphene Oxide Liquid Crystals with Polymer-Induced Depletion Attractions

et al. 2018

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“…Inclusion of polyelectrolytes can also induce substantial destabilization in colloids, where nonadsorbing polymers can induce depletion flocculation 53−55 and adsorbing polymers can induce flocculation by bridging. 53,56,57 In the latter case, particles act as cross-linkers between polymer molecules or vice versa. CS and HA contain repeat carboxylic acid moieties similar to poly(acrylic acid) and were hypothesized in this study to adsorb to the surface of the HAP particles via a similar mechanism.…”

Section: Discussionmentioning

confidence: 99%

Mapping Glycosaminoglycan–Hydroxyapatite Colloidal Gels as Potential Tissue Defect Fillers

et al. 2014

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Malleable biomaterials such as Herschel–Bulkley (H–B) fluids possess shear responsive rheological properties and are capable of self-assembly and viscoelastic recovery following mechanical disruption (e.g., surgical placement via injection or spreading). This study demonstrated that the addition of moderate molecular weight glycosaminoglycans (GAGs) such as chondroitin sulfate (CS) (Mw = 15–30 kDa) and hyaluronic acid (HA) (Mw = 20–41 kDa) can be used to modify several rheological properties including consistency index (K), flow-behavior index (n), and yield stress (τy) of submicrometer hydroxyapatite (HAP) (Davg ≤ 200 nm) colloidal gels. GAG–HAP colloidal mixtures exhibited substantial polymer–particle synergism, likely due to “bridging” flocculation, which led to a synergistic increase in consistency index (KGAG-HAP ≥ KGAG + KHAP) without compromising shear-thinning behavior (n < 1) of the gel. In addition, GAG–HAP colloids containing high concentrations of HAP (60–80% w/v) exhibited substantial yield stress (τy ≥ 100 Pa) and viscoelastic recovery properties (G′recovery ≥ 64%). While rheological differences were observed between CS–HAP and HA–HAP colloidal gels, both CS and HA represent feasible options for future studies involving bone defect filling. Overall, this study identified mixture regions where rheological properties in CS–HAP and HA–HAP colloidal gels aligned with desired properties to facilitate surgical placement in non-load-bearing tissue-filling applications such as calvarial defects.

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“…Note that in the literature often the synonymous name poly(ethylene oxide) has been used. , Grafting or adsorption of polymers is of general interest and typically influences the phase behavior, the stability of suspensions, the diffusion, and also the interaction potential. In the past, the majority of studies dealt with spherical colloids − but also the rodlike fd-virus has been studied extensively. − The wildtype fd-virus has a molar mass of 1.64 × 10 7 g mol –1 , a contour length ( L ) of 880 nm, a radius ( a ) of 3.4 nm, and a persistence length ( L P ) of 2.2 μm. The fd-virus consists of single-stranded DNA, coated with amino groups and acidic residues, which determine the surface properties of the fd-virus.…”

Section: Introductionmentioning

confidence: 99%

Thermophoresis of a Colloidal Rod: Contributions of Charge and Grafted Polymers

et al. 2019

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In this study we investigated the thermodiusion behavior of a colloidal model system as function of Debye length, λ DH , which is controlled by the ionic strength. Our system consists of an fd-virus grafted with polyethylene glycol (PEG) with a molecular mass of 5000 g/mol. The results are compared with recent measurements on bare fd-virus and results of PEG. The diusion coecients of both viruses are comparable and increase with increasing Debye length. The thermal diusion coecient, D T , of the bare virus increases strongly with the Debye length, while D T of the grafted fdvirus shows only a very weak increase. The Debye length dependence of both systems can be described with an expression derived for charged rods using the surface charge density and an oset of D T as adjustable parameters. It turns out that the ratio of the 1 determined surface charges is inverse to the ratio of the surfaces of the two systems, which means that the total charge remains almost constant. The determined oset of the grafted fd-virus describing the chemical contributions is the sum of D T of PEG and the oset of the bare fd-virus. At high λ DH , corresponding to low ionic strength, the S T-values of both colloidal model systems approach each other. This implies a contribution from the polymer layer, which is strong at short λ DH and fades out for the longer Debye lengths, when the electric double layer reaches further than the polymer chains and therefore dominates interactions with the surrounding water.

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Reduced colloidal repulsion imparted by adsorbed polymer of particle dimensions

Cited by 9 publications

References 62 publications

Tailored Colloidal Stability and Rheological Properties of Graphene Oxide Liquid Crystals with Polymer-Induced Depletion Attractions

Tailored Colloidal Stability and Rheological Properties of Graphene Oxide Liquid Crystals with Polymer-Induced Depletion Attractions

Mapping Glycosaminoglycan–Hydroxyapatite Colloidal Gels as Potential Tissue Defect Fillers

Thermophoresis of a Colloidal Rod: Contributions of Charge and Grafted Polymers

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