Title: Functional Soft Solids: A Foray into Gels, Aerogels and Nanofibrous Structures

Abstract

In this presentation, we will share vignettes of various research projects in our group, the focus of which have primarily been on multicomponent soft materials. Examples will be drawn from, various classes of polymeric, colloidal, nanoparticulate and biological systems, to elucidate the relationship between material microstructure/morphology, chemistry, formulation and macroscopic behavior. We hope to illustrate this notion by using a few examples: (a) hybrid polymer-inorganic aerogels, where ultra-light, yet mechanically robust aerogels are developed with multi-functionality (Adv. Funct. Mat. 2020; J. Mat. Chem. A 2024, Small Methods 2024). The degree of oleophilicity/hydrophobicity is exploited to render these materials useful in oil and chemical spill remediation while the nature of interaction between the polymer and inorganics (e.g., silica, MOF) is utilized to make this mechanically flexible, flame retardant, antibacterial and amenable to CO2 capture. (b) stimuli-driven polymer hydrogels wherein the use of UV, enzymes or shear are used as triggers to affect the sol to gel or gel to sol transitions in different systems. The underlying interactions, gelation mechanism and ultimate material restructuring are probed using rheology. We discuss the use of such approaches in diverse applications from fracking to coatings. Materials of interest include Pickering emulsions (JCIS 2020, ACS Sus. Chem. Eng. 2023), nanocellulose (Soft Matter 2020) and microgels laden with nanoparticles (JCIS 2021). (c) material platforms for improved food security, in which biodegradable colloidal particles, fibrous matrices or Pickering emulsions are used as agricultural solutions to establish sustainable agriculture globally (Curr Opinion in Coll Science 2020, Nature Food 2023, Adv Func. Mat 2025). Particles imbibed with active ingredients (e.g., fungicides) are developed via phase separation in water. The tunable release profile of the formulation controlled by interaction of the actives and polymers together with the variation in the morphology of the particles are explored for foliar applications (Adv Func Mat 2021). In a similar vein, fibrous matrices are used as seed wraps to prevent nematode infestation (Nature Sust, 2022, ACS Sus Chem Engg 2020). We discuss the use of this approach in field trials in Sub-Saharan Africa, and the role it can play there and other developing and developed nations in enhancing crop yield and quality.