Sat, 26 Jul 2008 17:18:50 BST CiteULike: dchen drying http://www.citeulike.org/user/dchen/tag/drying CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2878272 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 77, No. 2. (2008)</i><br /><br />Upon drying, colloidal suspensions undergo a phase transformation from a “liquid” to a “gel” state. With further solvent evaporation, tensile stresses develop in the gel, which ultimately leads to fractures. These generally manifest themselves in regular cracking patterns which reflect the physical conditions of the drying process. Here we show experimentally and theoretically how, in the case of a drying droplet of magnetic colloid (ferrofluid), an externally applied magnetic field modifies the stress in the gel and therefore the crack patterns. We find that the analysis of the shape of the cracks allows one to estimate the value of the gel Young's modulus just before the crack nucleation. When a crack is oriented by a magnetic field L Pauchard F Elias P Boltenhagen A Cebers JC Bacri doi:10.1103/PhysRevE.77.021402 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 77, No. 2. (2008) 2008-06-09T21:59:24-00:00 2008 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 77 2 APS 2008 colloids control drying field magnetic pre http://www.citeulike.org/user/dchen/article/2811002 <i>Physical Review Letters, Vol. 100, No. 19. (2008)</i><br /><br />Useful films can be formed by drying colloidal dispersions, but the negative capillary pressure generated often promotes cracks. Complex lateral flows during drying compromised previous measurements of the pressure required for cracking. Here we report data for the onset of cracking, and the additional cracks that appear at higher pressures, from high-pressure ultrafiltration experiments on homogeneously compressed films. A comparison of the data with expectations from theory confirms that cracking is controlled by elastic recovery, though an energy criterion only provides a lower bound. Our experiments also identify the role of flaws as nucleation sites that initiate cracks. Direct Measurements of Critical Stresses and Cracking in Thin Films of Colloid Dispersions Weining Man William Russel doi:10.1103/PhysRevLett.100.198302 Physical Review Letters, Vol. 100, No. 19. (2008) 2008-05-18T18:19:48-00:00 2008 Physical Review Letters 100 19 APS 2008 colloids drying experiment http://www.citeulike.org/user/dchen/article/2754715 <i>Physical Review Letters, Vol. 96, No. 8. (2006)</i><br /><br />We use pervaporation-based microfluidic devices to concentrate species in aqueous solutions with spatial and temporal control of the process. Using experiments and modeling, we quantitatively describe the advection-diffusion behavior of the concentration field of various solutions (electrolytes, colloids, etc.) and demonstrate the potential of these devices as universal tools for the kinetic exploration of the phases and textures that form upon concentration. Microevaporators for Kinetic Exploration of Phase Diagrams Jacques Leng Barbara Lonetti Patrick Tabeling Mathieu Joanicot Armand Ajdari doi:10.1103/PhysRevLett.96.084503 Physical Review Letters, Vol. 96, No. 8. (2006) 2008-05-05T00:02:09-00:00 2006 Physical Review Letters 96 8 APS 2006 cool crystal drying focus microrheology phase http://www.citeulike.org/user/dchen/article/2713887 <i>Physical Review Letters, Vol. 91, No. 22. (24 November 2003), 224501.</i> Flow and Fracture in Drying Nanoparticle Suspensions ER Dufresne EI Corwin NA Greenblatt J Ashmore DY Wang AD Dinsmore JX Cheng XS Xie JW Hutchinson DA Weitz doi:10.1103/PhysRevLett.91.224501 Physical Review Letters, Vol. 91, No. 22. (24 November 2003), 224501. 2008-04-24T18:38:32-00:00 2003 Physical Review Letters 91 22 224501 American Physical Society dinsmore drying weitz http://www.citeulike.org/user/dchen/article/2710298 <i>Physical Review Letters, Vol. 94, No. 1. (2005)</i><br /><br />Minute concentrations of suspended particles can dramatically alter the behavior of a drying droplet. After a period of isotropic shrinkage, similar to droplets of a pure liquid, these droplets suddenly buckle like an elastic shell. While linear elasticity is able to describe the morphology of the buckled droplets, it fails to predict the onset of buckling. Instead, we find that buckling is coincident with a stress-induced fluid to solid transition in a shell of particles at a droplet's surface, occurring when attractive capillary forces overcome stabilizing electrostatic forces between particles. Onset of Buckling in Drying Droplets of Colloidal Suspensions N Tsapis ER Dufresne SS Sinha CS Riera JW Hutchinson L Mahadevan DA Weitz doi:10.1103/PhysRevLett.94.018302 Physical Review Letters, Vol. 94, No. 1. (2005) 2008-04-23T21:45:07-00:00 2005 Physical Review Letters 94 1 APS colloids drying weitz http://www.citeulike.org/user/dchen/article/2709644 <i>Langmuir, Vol. 22, No. 14. (4 July 2006), pp. 6024-6030.</i><br /><br />Abstract: Spray drying of complex liquids to form solid powders is important in many industrial applications. One of the challenges associated with spray drying is controlling the morphologies of the powders produced; this requires an understanding of how drying mechanics depend on the ingredients and conditions. We demonstrate that the morphology of powders produced by spray drying colloidal polystyrene (PS) suspensions can be significantly altered by changing the molecular weight of dissolved poly(ethylene oxide) (PEO). Samples containing high-molecular-weight PEO produce powders with more crumpled morphologies than those containing low-molecular-weight PEO. Observations of drying droplets suspended by a thin film of vapor suggest that this occurs because the samples with high-molecular-weight PEO buckle earlier in the drying process when the droplets are larger. Earlier buckling times are likely caused by the decreased stability, demonstrated by bulk rheology experiments, of PS particles in the presence of high-molecular-weight PEO at elevated temperatures. We present a consistent picture in which decreased particle stability hastens droplet buckling and leads to more crumpled powder morphologies; this underscores the importance of interparticle forces in determining the buckling of particle-laden droplets. Buckling and Crumpling of Drying Droplets of Colloid-Polymer Suspensions Y Sugiyama RJ Larsen JW Kim DA Weitz doi:10.1021/la053419h Langmuir, Vol. 22, No. 14. (4 July 2006), pp. 6024-6030. 2008-04-23T17:51:21-00:00 2006 Langmuir 22 14 6024 6030 colloids drying weitz http://www.citeulike.org/user/dchen/article/2709642 <i>Langmuir, Vol. 22, No. 17. (15 August 2006), pp. 7144-7147.</i><br /><br />Abstract: We investigate the dynamics of fracture in drying films of colloidal silica. Water loss quenches the nanoparticle dispersions to form a liquid-saturated elastic network of particles that relieves drying-induced strain by cracking. These cracks display intriguing intermittent motion originating from the deformation of arrested crack tips and aging of the elastic network. The dynamics of a single crack exhibits a universal evolution, described by a balance of the driving elastic power with the sum of interfacial power and the viscous dissipation rate of flowing interstitial fluid. Dynamics of Fracture in Drying Suspensions ER Dufresne DJ Stark NA Greenblatt JX Cheng JW Hutchinson L Mahadevan DA Weitz doi:10.1021/la061251+ Langmuir, Vol. 22, No. 17. (15 August 2006), pp. 7144-7147. 2008-04-23T17:48:29-00:00 2006 Langmuir 22 17 7144 7147 drying dynamics film weitz