Tough Hydrogels for biomedical applications
Tissue engineering is a practice to assemble functional scaffolds that provide cell attachment to replace or improve damaged tissues or whole organs. Three-dimensional (3-D) extrusion printing provides an excellent platform to create a complex structured scaffold for tissue engineering. Bio-polymeric hydrogels are attractive materials to create bio-scaffolds. However, due to the lack of mechanical strength of soft biopolymers such as chitosan (CH), it is difficult to fabricate precisely controlled native tissue-mimicking architectures. Various polymers, nanofillers, and crosslinkers are added to improve the functionality and mechanical strength of CH scaffolds. Rheological characterization plays a key role in the 3-D printing of soft materials. The printability is primarily ascribed to the rheological properties of shear thinning, adequate viscosity, and yield stress to support the layer-by-layer structure and the excellent fidelity of the filaments. The mechanical strength of the printed filaments should be sufficiently high to self-support and prevent the distortion of the scaffolds induced by the gravity of the deposited filaments. This work aims to improve the CH strength by adding low quantity graphene oxide nanosheets. The GO embedded CH hydrogel is proven to be a promising candidate for a tissue engineering application as it supported the differentiation of SH-SY5Y cells.
Mechanically tunable suspensions of 2D colloids and their applications
Graphene oxide is a well-known 2D nanomaterial, with lateral dimensions of microns and thickness in nanometers. A single layer of GO, due to its homogeneity, large surface area (2630 m2g-1), and occupancy of chemically active surface functional groups have a high adsorption capability. Utilizing these properties, the scientific community has established its decontamination potential for a spectrum of organic substances related to various industries. However, the recovery of GO from water requires ultrahigh centrifugation for an extended time, which significantly increases the process costs and difficulty. Further, the long-term exposure to these graphene-family nanomaterials (GFN’s) to water is reported to be toxic. To overcome the secondary pollution, the work in the group aims to prepare the 3D architecture of graphene oxide and its derivatives by utilizing polymers and/or electrolytes. Utilizing rheological characterization, we also study how mechanical properties can be tuned by varying the parameters of colloid concentration and the nature of dispersing medium.
Colloids in Liquid Crystals – Structure and Influence of External Fields
Liquid crystals (LCs) are anisotropic fluids with molecules arranged in a particular fashion; examples include nematic, smectic, hexagonal liquid crystals. The particles-in-Liquid Crystals composites have the capability to serve as the promising candidate for enhancing the inherent characteristics of the LCs which can open new avenues for sensing, display, and photochemical applications. The complexity and variety of hierarchical self-organized structures coupled with the high mechanical strength induced by the addition of the small fraction of colloidal or nanoparticles have continuously attracted the attention of the soft matter scientific community. Including colloidal particles leads to the self-assembly of the particles into sheets, rows, etc. The work in the group aims to understand the conditions under which particle self-assembly occurs and their influence on the overall flow properties.
Concentrated Mineral Slurries
Various conventional transportation techniques such as train, truck, barge, and conveyors for slurry transportation have limitations on the amount of solids and the distance to be transported. On the other hand, the hydraulic conveying of solids in the slurry form through pipelines offers many advantages over other modes of transportation such as minimum environmental disruption, low air, and noise pollution, minimum en-route losses, less space required for installation, low operating and maintenance expenditure, feasible in difficult terrains, and insensitive to the surface conditions. One of the major concerns related to pipeline transportation of slurries is obtaining a favorable flow behavior in terms of minimum energy consumption, frictional head losses, and energy cost when bulk solids are transported through long pipelines. The feasibility of a favorable slurry flow in the pipeline is mainly governed by slurry properties, flowing conditions, and pipeline design parameters. Thus, rheological studies play a crucial role in describing the flow characteristics of the slurry in the pipeline. In collaboration with faculty from materials science, we are understanding the interplay of surface-active agents, particle concentration, particle size distribution, coarse particles addition, applied shear, time, and temperature on the mineral slurries’ (coal, fly ash, bauxite, etc. ) rheology and subsequently the slurry transportation in pipelines.
Many day-to-day consumer products such as creams are either foams or emulsions. A significant challenge is to stabilize these systems as they phase separate over time. The work in the group aims to understand high internal phase emulsions (where drop phase is greater than 50%) in the presence of proteins as stabilizers.