个人简介

Bio Professor Lynn Walker is currently Professor of Chemical Engineering with courtesy appointments in Chemistry and in Materials Science & Engineering. Prof. Walker received her BS Chemical Engineering degree from the University of New Hampshire in 1990 and her PhD from the University of Delaware in 1995, under the supervision of Norman Wagner. After holding a postdoctoral position at Katholieke Universiteit Leuven, Leuven Belgium, Prof. Walker joined Carnegie Mellon's Department of Chemical Engineering in 1997. Prof. Walker was a Visiting Professor during a sabbatical at Polymer IRC, University of Leeds in 2007. Education Ph.D., 1995, University of Delaware B.S., 1990, University of New Hampshire

研究领域

Polymer

Research in the Complex Fluids Rheology group focuses on understanding and controlling complex, or structured, fluids in engineering applications. Our work is primarily experimental and involves rheometric characterization, classical colloid and macromolecular analytical techniques, small-angle scatterning and microfluidic tools. We collaborate closely with others in the Center for Complex Fluids Engineering. Two main themes, Impact of Nanoscale Structure on Rheology and Behavior of Complex Systems with Fluid-Fluid Interfaces, run through the group and our interests lie in applying fundamental knowledge and ideas to real engineering situations. Impact of Nanoscale Structure on Rheology: Relatively weak forces at the molecular level dictate the macroscopic properties, particularly the flow properties, of complex fluids. To effectively process and control these fluids, we need to understand the flow-structure relationship for different types of structured fluids and how molecular structure influences this coupling. While the intermolecular forces of importance act over nanometers, the structures formed span nanometers through microns; the timescales associated with response of these structures fall in the range of most processing flows. Work in the group combines rheology with scattering techniques to tackle and quantify the flow-structure coupling. A number of structured fluids have been considered by the group; liquid crystal polymers, polymer blends, surfactant mesophases, wormlike micelles and block copolymers. Behavior of Complex Systems with Fluid-Fluid Interfaces: Fluid-fluid interfaces deform readily in external fields and are sensitive to molecular transport from the bulk. Molecular adsorption to interfaces changes the interfacial tension and constitutive behavior of those interfaces. The response of a system containing fluid-fluid interfaces (emulsions, foams, bubbly liquids) to mechanical or other deformation is dependent on these interfaces. Earlier work on sprays, atomization, microfluidic droplet formation and polymer blends convinced us that there needs to be improved understanding of the details of the interfaces and mechanics. We have been developing devices and approaches to the characterization of complex interfaces and interfaces in contact with complex (i.e., nonNewtonian) bulk phases. Tools include microscopy, device development, soft lithography, and rheology.

近期论文

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“Shear orientation of nanoparticle arrays templated in a thermoreversible block copolymer micellar crystal,” D. C. Pozzo and L. M. Walker, accepted Macromolecules (2007) “Polymerized rod-like micelle adsorption at the solid-liquid interface,” S. Biggs, M. Labarre, C. Hodges, L. M. Walker and G. Webber, accepted Langmuir (2007) “Solution behavior of rod-like polyelectrolyte surfactant aggregates polymerized from wormlike micelles,” D.M. Kuntz and L. M. Walker, in press J. Physical Chemistry B (2007) “Multisegmented Block Copolymers by “Click” Coupling of Polymers Prepared by ATRP,” P. L. Golas, N. V. Tsarevsky, B. S. Sumerlin, L. M. Walker and K. Matyjaszewski, accepted Austral. J. Chemistry (2007) “Dynamic Wetting of Boger Fluids,” Y. Wei, G. K. Seevaratnam, S. Garoff, E. Ramé and L. M. Walker, in press JCIS doi:10.1016/j.jcis.2007.04.020 (April 2007) “Dynamic Wetting by Non-Newtonian Fluids: Shear Thinning Fluids,” G. K. Seevaratnam, Y. Suo, E. Ramé, L. M. Walker and S. Garoff, Physics of Fluids 19:012103 (2007) “Small angle neutron scattering of silica nanoparticles templated in PEO-PPO-PEO cubic crystals,” D. C. Pozzo and L. M. Walker, Coll. Surfaces A (2007), 294:117-129 “Quantifying Air-Atomization of Viscoelastic Fluids through Fluid Relaxation Times,” Y. Christanti and L. M. Walker, Atomization & Sprays 16(7):777-790 (2006) “Controlling Dimensions of Polymerizeable Micelles: Micelle Template versus Reaction Conditions,” M. J. Gerber and L. M. Walker, Langmuir 22:941-948 (2006) “Dose-Dependent Cell Growth in Response to Concentration Modulated Patterns of FGF-2 Printed on Fibrin,” E. D. Miller, G. W. Fisher, L. M. Walker, L. E. Weiss and P. G. Campbell, Biomaterials 27:2213-2221 (2006) “Engineered Spatial Patterns of FGF-2 Immobilized on Fibrin Direct Cell Organization,” P. G. Campbell, E. D. Miller, G. W. Fisher, L. M. Walker and L. E. Weiss, Biomat 26:6762-6770 (2005) “Three-dimensional nanoparticle arrays templated by self-assembled block-copolymer gels,” D. C. Pozzo and L. M. Walker, Macromolecular Symposium 227(1):203-210 (2005) “A Bayesian Modeling Approach to Computer-Aided Experimental Design of Heterogeneous Matrices for Tissue Engineering Applications,” L. E. Weiss, C. H. Amon, E. D. Miller, D. Romero, I. Verdinelli, L. M. Walker and P. G. Campbell, Computer-Aided Design 37(11):1127-1139 (2005) “Rheology and Phase Behavior of Copolymer-Templated Nanocomposite Materials,” D. C. Pozzo, K. R. Hollabaugh and L. M. Walker, J. Rheology 49(3):759-782 (2005) “Dynamic Wetting of Inelastic Polymer Melts,” G. K. Seevaratnam, L. M. Walker, E. Ramé and S. Garoff, J. Coll. & Interface Science 284:265-270 (2005) “Characterization of Rod-Like Aggregates Generated from a Cationic Surfactant and a Polymerizable Counterion,” M. J. Gerber, S. R. Kline and L. M. Walker, Langmuir 20(20):8150-8516 (2004) “Reversible Shear Gelation of Clay-Polymer Dispersions” D. C. Pozzo and L. M. Walker Colloids & Surfaces A 240:187-198 (2004) “Rheology of Transient Networks Containing Hydrophobically Modified Cellulose, Anionic Surfactant and Colloidal Silica: Role of Selective Adsorption,” K. D. Berglund, M. T. Truong, T. M. Przybycien, R. D. Tilton and L. M. Walker, Rheol. Acta 43(1):50-61 (2004) “The Adsorption of Polymerized Rod-like Micelles at the Solid-Liquid Interface,” S. Biggs, S. R. Kline and L. M. Walker, Langmuir 20(4):1085-1094 (2004) “Shear Induced Gelation of Laponite-PEO Mixtures,” J. Zebrowski, V. Prasad, W. Zhang, L. M. Walker and D. A. Weitz, Coll. Surf. A 213(2-3):189-197 (2003)