Nanocolloidal Assembly

The assembly of nanocolloids into useful structures has long been a key aim of chemical engineers and material scientists. We address this challenge by synthesizing anisotropic colloids and self-assembling them with the assistance of applied electric, shear and gravitational fields. In a second effort, we address the fact that the typical size of the ordered arrays that have been produced in academia is currently too small for real-world applications. In collaboration with Professors Ron Larson and Sharon Glotzer, we have investigated the complex fluid dynamics of large-scale methods for colloidal crystal production, such as spin coating.

Related Publications:

  1. 1.Shah, A.A., Schultz, B., Zhang, W., Glotzer, S.C. and Solomon, M.J., “Actuation of shape-memory colloidal fibres of Janus ellipsoids,” Nature Materials, 14, 117-124 (2015).

  1. 2.Lilian C. Hsiao, Benjamin A. Schultz, Jens Glaser, Michael Engel, Megan E. Szakasits, Sharon C. Glotzer & Michael J. Solomon, “Metastable orientational order of colloidal discoids,” Nature Communications, 6, 8507 (2015).

  1. 3.Laura Colón-Meléndez, Daniel J. Beltran-Villegas, Greg van Anders, Jun Liu, Matthew Spellings, Stefano Sacanna, David J. Pine, Sharon C. Glotzer, Ronald G. Larson, and Michael J. Solomon. "Binding kinetics of lock and key colloids," The Journal of Chemical Physics, 142 (2015).

Contact Current Post Docs & Graduate Students:

Dr. Carlos A. Silvera Batista

Dr. Sepideh Razavi

Tianyu Liu

Megan Szakasits

Peng-Kai Kao

Keara Saud

Bacterial Biofilms

With Dr. Scott Van Epps of the U-Michigan department of Emergency Medicine and collaborators at two other universities, we are exploring the biomechanical properties of bacterial biofilms. Biofilms are colonies of microoganisms that are pervasive in a range  of natural and industrial settings. They can also grow on devices, such as intravascular catheters, that are introduced into the body as part of medical practice. Biofilm structure and mechanics is thought to play a protective role by, for example, improving the resistance of baccteria to antibiotic treatments. The aim of this project is to understand and measure the mechanical properties of biofilms of size about 10-100 microns, since these dimensions match the scales relevant to medical practice.

Related Publications:

  1. 1.Pavlovsky, L., Sturtevant, R.A., Younger, J.G., and Solomon, M.J., “Effects of Temperature on the Morphological, Polymeric, and Mechanical Properties of Staphylococcus epidermidis Bacterial Biofilms,” Langmuir (2015).

  2. 2.Elizabeth J. Stewart, Mahesh Ganesan, John G. Younger & Michael J. Solomon, “Artifical Biofilms establish the role of matrix interactions in staphylococcal biofilm assembly and disassembly,” Scientific Reports, 5, 13081 (2015).

  3. 3.Pavlovsky, L., Ganesan, M., Younger, J.G., and Solomon, M.J., “Elasticity of microscale volumes of viscoelastic soft matter by cavitation,” Applied Physics Letters, 2014, 105, 114105.

  4. 4.Stewart, E.J., A.E. Satorius, J.G. Younger, and Solomon, M.J., “Role of Environmental and Antibiotic Stress on Staphylococcus epidermidis Biofilm Microstructure,” Langmuir, 2013, 29 (23), 7017-7024.

Contact Current Post Docs & Graduate Students:

Dr. Mahesh Ganesan

Nina Gasbarro

Maria Ma

Joanne Beckwith

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Colloidal Gelation

Structural rigidity is the governing principle used in the construction of bridges, buildings, and domes that are capable of withstanding large loads. Our group has experimentally observed structural rigidity in colloidal gels. We are able to capture the 3D microstructure of attractive gels undergoing high-rate, large-deformation shearing using confocal microscopy.By analyzing structurally rigid clusters, we find a previously hidden subpopulation of colloids that are highly predictive of the non-linear elasticity of yielded gels, and confirm their rigidity by means of Brownian dynamics simulation. Because our experimental conditions are analogous to the large-strain, high flow rates used in the processing of advanced materials, our understanding of gel rheology can be applied to the flow of glassed, crystals, and granular materials. We offer a compelling argument that can be used as a conceptual framework to predict the rheology of soft matter based on its microstructure. 

Related Publications:

  1. 1.Hsiao, L.C., Newman, R.S., Glotzer, S.C. and Solomon, M.J., “Role of isostaticity and load-bearing microstructure in the elasticity of yielded colloidal gels,” PNAS, 2012, 109 (40), 16029-16034.

Contact Current Graduate Student:

Megan Szakasits