Understanding the microstructure and viscoelasticity of anisotropic particles

A particle whose aspect ratio deviates from unity is referred to as anisotropic. Consequently, materials constituting anisotropic particles may have direction-dependent properties. Anisotropic materials are often encountered in nature in their simplest form of rods (prolate) and discs (oblate). While the red blood cells and natural swelling clays are oblate, different kinds of bacteria, viruses and proteins are prolate. The anisotropic materials have gained significant interest in the past few years, owing to their unique property of direction-dependent behaviors, percolation at small concentrations, and high surface to volume ration. The rich literature on this subject includes but is not limited to the synthesis of a spectacular array of particles with different patterns, shape and functionalities. The anisotropic shape and interactions have emerged as a powerful tool for many applications which desire low particle volume fraction and high specific surface area.

Previously, I focused on understanding the microstructure and viscoelasticity of colloidal gels [1, 2, 4-7] and polymer gels [3]. At present, I am working on synthesizing anisotropic hollow prolate particles with well-defined aspect ratios. The temperature-induced interactions among the anisotropic nanoparticles lead to self-assembly of the particles upon decreasing the temperature. An investigation of the anisotropic hollow rod-like particles with short range interactions using rheology, microscopy and scattering is expected to render profound insights regarding the microstructure. A detailed knowledge of the phase behavior and viscoelasticity of these anisotropic systems will be beneficial in designing novel applications of these particles as drug delivery carrier and nanoreactors.

Publications

1. Suman K., Joshi Y. M. “Kinetic model for a sol-gel transition: Application of the modified Bailey criterion”, Rheologica Acta 59 (2020), 745-753.
2. Suman K., Joshi Y. M. “On the universality of the scaling relations during sol-gel transition”, Journal of Rheology 62 (2020) 863-877, (Feature Article and Scilight story).
3. Joshi N.,^a Suman K.,^a Joshi Y. M., “Rheological Behavior of Aqueous Poly (vinyl alcohol) Solution During a Freeze-Thaw gelation Process” Macromolecules 53 (9), 3452-3463, (Cover Art).
4. Suman K., Mittal M., Joshi Y. M., “Effect of sodium pyrophosphate and understanding microstructure of aqueous LAPONITE^® dispersion using dissolution study” Journal of Physics: Condensed Matter 32 (2020), 224002.
5. Suman K., Joshi Y. M. “Analyzing onset of nonlinearity of a colloidal gel at the critical point”, Journal of Rheology 63 (2019), 991-1001, (Cover Art).
6. Suman K., Joshi, Y. M. “Microstructure and Soft Glassy Dynamics of Aqueous Laponite Dispersion”, Langmuir 34 (2018), 13079-13103, (Invited Feature Article and Cover Art).
7. Mohanty RP, Suman K., Joshi Y. M., “In situ ion induced gelation of colloidal dispersion of Laponite: Relating microscopic interactions to macroscopic behavior”, Applied Clay Science 138, 17-24.

^a Both authors contributed equally to this manuscript.