Federal University of São Carlos (UFSCar), Department of Materials Engineering (DEMa), São Carlos, Brazil
Caio G. Otoni is an Assistant Professor of Materials Engineering/Polymer Science at the Federal University of São Carlos (UFSCar; as of 2020), from where he received his Ph.D. in Materials Science and Engineering (2017) in a dual affiliation with Embrapa Instrumentation. Food Engineer by training, Dr. Otoni was a postdoctoral researcher at the Institute of Chemistry of the University of Campinas (Unicamp; 2017–2020) and a visiting scholar at the Department Bioproducts and Bioprocesses of Aalto University (2019), both dealing with the physical chemistry of biocolloids. Also, Dr. Otoni joined the Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali (DICAM) of Università di Bologna (UNIBO; 2023) as a visiting professor, working on the polymerization of ionomers from bio-based monomers and the chemical recycling of polyesters, as well as the Agricultural Research Service (ARS) of the United States Department of Agriculture (USDA; 2010–2011), working on food packaging. Dr. Otoni was one of the 2023 Materials Today Rising Star Award recipients and currently serves as an Early Career Editorial Board member of Materials Today Bio and ACS Sustainable Chemistry & Engineering. His research is centered on polymer circularity, biomass valorization, and the assembly of biopolymers and biocolloids into multifunctional materials for food, biomedical, and agricultural applications.
Electrostatic complexation will be the core of this talk for enabling a green, simple, and reversible –yet strong– means of assembling wet colloidal systems and solid-state materials[1]. Nanocelluloses will be showcased as our building blocks of choice for supramolecular materials that are sustainable and that deliver engineered performance[2]. As cellulose inherently is not charged enough electrically, this presentation will cover different protocols for attaching positive and negative groups onto the surface of nanostructured celluloses, both nanofibrils and nanocrystals, a range of chemical (e.g., TEMPO-mediated oxidation, sulfuric acid hydrolysis, and grafting of quaternary ammonium compounds, such as EPTMAC or Girard’s reagent T) and physical (e.g., adsorption of soluble polycations and polyanions or cationic or anionic surfactants) routes. When charged, nanocellulosic particles find use in a wide range of applications, herein showcased by the kinetic stabilization of multiphase systems such as Pickering emulsions[3], biocidal surfaces[4], host/guest delivery systems, reversibly assembled dry and wet foams, rheology modifiers in complex fluids, and solid-state nanocomposites boasting suitable filler/matrix stress transfer. In these oppositely charged species, charge is compensated intrinsically (i.e., complexation) or extrinsically (i.e., screening by small electrolytes), offering a supramolecular toolbox for controlling the assembly and, importantly, the disassembly profiles in a straightforward fashion towards responsiveness and ‘physical’ recyclability.
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