Colloidal interactions and micromechanics in 2D and 3D gels

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ABSTRACTProposal Number: 0553656Principal Investigator: Furst, EricAffiliation: University of DelawareProposal Title: Colloidal interactions and micromechanics in 2D and 3D gelsIntellectual Merit.This work will investigate interfacial phenomena and interactions that underlie the properties of colloidal aggregates. This will be accomplished using novel experiments based on optical trapping, which enable directly assembly of model aggregates from individual colloids and controlled deformation with simultaneous measurement of microscopic stresses. The mechanics to be studied, unrecognized until now, have considerable consequences for the processing and properties of particulate gels, because of their influence on the yield stress, aging properties and moduli of these materials. The interactions and mechanics of two-dimensional colloidal systems will be investigated. Because particulate gels occur in a wide variety of manufacturing processes, including coatings, pharmaceutical formulations, ceramic parts manufacturing, mineral recovery and lubricant degradation, there is considerable interest in the ability to predict and control their properties. Two-dimensional systems are important due to the use of colloids for controlling the interactions in dispersed fluid phases (i.e. Pickering emulsions.) Although there have been notable advances in recent years, the fundamental mechanisms of the mechanical and rheological properties of particulate gels based on interparticle interactions, microstructure and micromechanics have yet to be fully understood. By studying the nano- and micro-scale physics, the fundamentals needed to synthesize new materials, and improve the prediction and control of product and processing properties in existing materials will be established. Furthermore, the understanding and control of colloidal interactions extends beyond gel rheology to novel and emerging applications, such as photonic crystals, chembiosensors and nanotechnology. Broader Impacts. This work will provide education and research training for one graduate student and one undergraduate research assistant in the technologically-critical fields of colloid science and interfacial phenomena. The training experience will be significantly enhanced through international and industrial collaborations. Results of this research will reach a broad community of scientists and engineers through publications in journals and presentations at national and international scientific meetings, including informal participation of the PI and his graduate students in the European Union SOFTCOMP Network of Excellence. The educational impact will be enhanced through short course instruction, lectures provided at KU-Leuven, and the organization of a symposium on the applications of laser tweezers in complex and colloidal fluids.