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Particle - Polymer reversible gel formation: Shake gels
During my time at Imperial College London, my research focused on investigating the behavior of shake gels—a class of reversible, shear-responsive materials formed by mixing colloidal particles with high molecular weight polymers in aqueous environments. These systems exhibit a fascinating transition: under mechanical agitation, they transform from low-viscosity liquids into gel-like structures, and upon resting, they slowly return to their liquid state. This reversible gelation is driven by physical interactions between the dispersed components and is of growing interest for applications across materials science, pharmaceuticals, consumer products, and environmental technologies.
The goal of the work was to explore and understand the fundamental principles that govern the gelation and relaxation behavior of these materials. Using rheological methods, the study examined how various physical and chemical factors—including concentration, temperature, flow conditions, and additives—affect the kinetics and structure of the gels. Emphasis was placed on capturing both the onset of gelation under shear and the recovery process during relaxation, using real-time measurements to quantify changes in viscosity and viscoelastic properties.
A major part of the research was devoted to understanding how the interaction between the polymer and colloidal components is influenced by their surrounding environment. Changes in formulation and external conditions were found to significantly affect how quickly gels form, how strong or elastic they become, and how long they take to return to their liquid state. These insights helped build a broader picture of how particle-polymer networks can be dynamically tuned, offering a framework for designing smart, responsive materials.
By combining experimental rigor with systematic variation of key parameters, the work contributed to a deeper understanding of soft matter systems. The findings provide a foundation for tailoring the behavior of reversible gels for real-world applications where control over mechanical response and temporal stability is essential.
Impact dynamics of polymer and emulsion droplet on nonwetting surface
This project explored the complex impact behavior of liquid droplets on nonwetting, superhydrophobic surfaces—an area of growing importance across industries such as agriculture, printing, coatings, and surface engineering. The study was conducted at the Indian Institute of Science, Bengaluru, and focused on understanding how liquid formulation and material properties influence droplet spreading, retraction, and rebound under dynamic conditions.
The research examined the impact dynamics of both aqueous polymeric solutions and emulsions with varied physical properties. The main aim was to identify how changing the internal structure of droplets—through additives that modify viscosity and interfacial properties—can enhance their ability to remain on superhydrophobic surfaces, which are typically resistant to wetting. A particular motivation for this work stemmed from practical challenges in fields like agricultural spraying, where droplet rebound from plant surfaces leads to significant material loss and environmental contamination.
By systematically varying the internal composition of the droplets, it was observed that certain formulations were highly effective in suppressing rebound, even at low additive concentrations. High-speed imaging and rheological analysis were used to capture the spreading and retraction behavior, revealing that while the spreading phase was largely governed by inertial and surface tension forces, the retraction dynamics were significantly affected by viscoelastic properties and surface interactions.
A key insight from this work was the observation that specific formulations promoted better adhesion through the formation of microscopic structures at the contact line, which slowed retraction and inhibited bouncing. These effects became more pronounced under higher impact velocities, showing robustness across a range of conditions.
The findings offer valuable strategies for improving droplet retention in systems where surface repellency is a barrier, without relying on toxic surfactants or high additive loads. The results have broad relevance to both scientific understanding and practical engineering of fluid–surface interactions, especially where control over droplet dynamics is critical.
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