Hydrodynamic properties of aqueous dextran solutions

Xue-lin, XU; Li, Hangquan; Zhang, Zhengdong; Qi, Xin

doi:10.1002/app.29043

Cited by 7 publications

(5 citation statements)

References 18 publications

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“…Video S1 shows the behavior of the viscous stock solutions of dextran and PEO. Consistent with other reports of the viscoelastic behavior of dextrans of various molecular weights and concentrations, , as well as our previous work, the solution of 50 wt % dextran behaved as a Newtonian fluid, although some studies have observed modest shear-thinning behavior for high molecular weight dextrans of 30 wt % or above attributed to presence of branches within the dextran chains . In contrast, PEO behaved as a non-Newtonian shear-thinning fluid at all concentrations above those sufficient for entanglement to occur, which was consistent with previous reports of the rheology of aqueous solutions of PEO. , Contrary to dextran solutions, for which we previously showed that the time scale for fiber formation was purely controlled by the entanglement dynamics, this implies that the time scale for fiber formation from the PEO solution is controlled by the entanglement dynamics and by a shear strain rate-dependent thinning process such as the elastocapillary regime described by Dinic and Sharma …”

Section: Results and Discussionsupporting

confidence: 92%

Formation of Core-Sheath Polymer Fibers by Free Surface Spinning of Aqueous Two-Phase Systems

2022

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Core-sheath fibers have numerous applications ranging from composite materials for advanced manufacturing to materials for drug delivery and regenerative medicine. Here, a simple and tunable approach for the generation of core-sheath fibers from immiscible solutions of dextran and polyethylene oxide is described. This approach exploits the entanglement of polymer molecules within the dextran and polyethylene oxide phases for free surface spinning into dry fibers. The mechanism by which these core-sheath fibers are produced after contact with a solid substrate (such as a microneedle) involves complex flows of the phase-separating polymer solutions, giving rise to a liquid–liquid core-sheath flow that is drawn into a liquid bridge. This liquid bridge then elongates into a core-sheath fiber through extensional flow as the contacting substrate is withdrawn. The core-sheath structure of the fibers produced by this approach is confirmed by attenuated total reflection Fourier-transform infrared spectroscopy and confocal microscopy. Tuning of the core diameter is also demonstrated by varying the weight percentage of dextran added to the reservoir from which the fibers are formed.

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Section: Results and Discussionsupporting

confidence: 92%

Formation of Core-Sheath Polymer Fibers by Free Surface Spinning of Aqueous Two-Phase Systems

2022

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“…To characterize non-spherical samples, we prepared a highly viscous medium composed of aqueous dextran (35% by weight) in 3.00 M MnCl 2 ; for this solution, we measured  m = 1.385 g/cm 3 . This highly viscous liquid (viscosity ~10 Pa•s, 18 or approximately that of honey) enabled us to use viscous drag to "pick up" the sample and rotate it with the container, about the z-axis. Figure 2 shows a schematic of this procedure: after rotating the container by 180 and then stopping, the sample fell gradually back to the bottom surface of the container.…”

Section: Experimental Expanding the Range Of Levitated Densities By Rmentioning

confidence: 99%

“…For powders of glass and aluminum, we used a solution with no added dextran. For tin and copper powders, we added 10% (by weight) dextran (viscosity ~ 0.2 Pa•s) 18 . For gold powder, we added 35% dextran (by weight).…”

Section: Experimental Expanding the Range Of Levitated Densities By Rmentioning

confidence: 99%

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Tilted Magnetic Levitation Enables Measurement of the Complete Range of Densities of Materials with Low Magnetic Permeability

et al. 2016

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Magnetic levitation (MagLev) of diamagnetic or weakly paramagnetic materials suspended in a paramagnetic solution in a magnetic field gradient provides a simple method to measure the density of small samples of solids or liquids. One major limitation of this method, thus far, has been an inability to measure or manipulate materials outside of a narrow range of densities (0.8 g/cm 3 <  < 2.3 g/cm 3 ) that are close in density to the suspending, aqueous medium. This paper explores a simple method-"tilted MagLev"-to increase the range of densities that can be levitated magnetically. Tilting the MagLev device relative to the gravitational vector enables the magnetic force to be decreased (relative to the magnetic force) along the axis of measurement. This approach enables many practical measurements over the entire range of densities observed in matter at ambient conditions-from air bubbles ( ≈ 0) to osmium and iridium ( ≈ 23 g/cm 3 ). The ability to levitate, simultaneously, objects with a broad range of different densities provides an operationally simple method that may find application to forensic science (e.g., for identifying the composition of miscellaneous objects or powders), industrial manufacturing (e.g., for quality control of parts), or resource-limited settings (e.g., for identifying and separating small particles of metals and alloys). INTRODUCTIONMagnetic levitation (MagLev) of diamagnetic or weakly paramagnetic materials suspended in a paramagnetic solution in a magnetic field gradient provides a simple method to measure density. [1][2][3][4] Based the balance of gravitational and magnetic forces, this method has four important capabilities and types of applications that make it attractive for use in a variety of settings. i) MagLev offers the ability to resolve small differences in the densities of samples (e.g., pastes, gels, heterogeneous solids, small particles, crystal polymorphs) 1,2,4-7 with physical properties that make them difficult or impossible to analyze by other instruments (e.g., density gradient columns, pycnometers, oscillating-tube densometers). 8 ii) MagLev can be used for complex, shape-based tasks, such as noncontact, three-dimensional self-assembly, 9,10 orientation control 11 , and quality control 12 of a wide variety of polymeric components. iii) MagLev can be used to perform a range of important, density-based bioanalyses. [13][14][15][16][17] iv) The simplicityof-use, portability, and low cost of MagLev make it particularly attractive for use in resource-limited settings (e.g., schools, mines, archeological sites, field operations, and laboratories in the developing countries).Despite these advantages, one major limitation, thus far, has been an inability to measure or manipulate materials outside of

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“…In conclusion, the average degree of polymerization of poly[(1,6-bis(N-methylimidazolium)hexa-2,4-diyne)dibromide] lies between 15 and 35 with a polydispersity index of about 1.2 and a weight average hydrodynamic radius of 1.77 nm. Higher concentrations in dextran (up to 30% with a lower molar mass polymer for limiting the increase in viscosity) 62 could increase the resolution of the oligomeric polydiacetylene separation. Indeed, it has been reported in a previous work 63 that no separation of DNA oligomers could be achieved using a 10% dextran solution while excellent baseline separation was obtained with a 30% dextran concentration.…”

Section: Discussionmentioning

confidence: 99%

Size-Based Characterization of an Ionic Polydiacetylene by Taylor Dispersion Analysis and Capillary Electrophoresis

et al. 2009

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International audienceThis work focuses on the size-based characterization of a water-soluble ionic polydiacetylene with a polycationic structure, poly-[(1,6-bis(N-methylimidazolium)hexa-2,4-diyne)dibromide]. This polymer could not be characterized using classical analytical techniques such as size-exclusion chromatography and MALDI−TOF mass spectrometry due to problems of purification, low quantities available, and difficult laser desorption. The work presented here demonstrates the interest and the complementarity of two independent analytical methods, Taylor dispersion analysis (TDA) and capillary electrophoresis (CE), that require only very small amounts of sample (only a few nanoliters are injected) and that can be easily implemented on commercially available capillary electrophoresis apparatus. TDA is a nonseparative method that allows the absolute determination of the average hydrodynamic radius of the polymer. This method does not require the determination of the polymer concentration in the sample and is not perturbed by the presence of residual monomer. Since the average hydrodynamic radius determined by this method is a weight average value, it also gives information complementary to the average value derived from dynamic light scattering measurements. Simple hydrodynamic modeling allows estimation of a minimal value for the average degree of polymerization. Free solution CE can be used for monitoring the polymerization process and quantifying the degree of conversion. Furthermore, entangled polymer solution CE was used as a size-based separation technique for the characterization of the molar mass distribution using calibration with polyvinylpyridine standards. Number and weight molar mass distributions of the sample were obtained relative to this calibration

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Hydrodynamic properties of aqueous dextran solutions

Cited by 7 publications

References 18 publications

Formation of Core-Sheath Polymer Fibers by Free Surface Spinning of Aqueous Two-Phase Systems

Formation of Core-Sheath Polymer Fibers by Free Surface Spinning of Aqueous Two-Phase Systems

Tilted Magnetic Levitation Enables Measurement of the Complete Range of Densities of Materials with Low Magnetic Permeability

Size-Based Characterization of an Ionic Polydiacetylene by Taylor Dispersion Analysis and Capillary Electrophoresis

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