Institute of Chemistry – State University of Campinas
Menu
Prof. Loh has a degree in Industrial Chemistry from the Federal University of Rio Grande do Sul (1986) and a PhD in Chemistry from the State University of Campinas (1992). Completed a postdoctoral internship at the Chemical Laboratory of the University of Kent at Canterbury, UK (1992-1994) and was a visiting researcher at the Division of Physical Chemistry 1 of the University of Lund, Sweden (2003-2004) and Visiting Professor at Univ Porto (2014) and University of Osaka (2019 and 2023). Currently, he is a full professor at the State University of Campinas, former director of the Institute of Chemistry at UNICAMP (2010-2014). He is the Editor of ACS Sustainable Chem & Eng (since 2023), and was an Editor of the Journal of the Brazilian Chemical Society from 1999 to 2017, and an associate editor of the Journal of Surfactants and Detergents (since 2009). He is a member of the Advisory Board
of the Journal of Chemical Thermodynamics, Chemical Sciences, Langmuir (2013-2016), and ACS Omega (since 2018). He is currently the Deputy Coordinator of Multiuser Equipment at FAPESP, and is the appointed chair for the International Symposium on Polyelectrolytes , 2025. He has experience in the field of Chemistry, with emphasis on Chemical Thermodynamics and Physical Chemistry of Colloids, working mainly on polymer and/or surfactant solutions, phase equilibrium and structures in complex fluids, nanocellulose and other renewable colloids, colloidal chemistry of petroleum and fuels, and calorimetry applications.
Coacervates are formed from the associative phase separation displayed by mixtures of oppositely-charged species, such as polymers (or biopolymers), surfactants (or their aggregates) and nanoparticles. The coacervate macroscopic phase separation can be restricted to nanometric dimensions if a neutral-charged block copolymer is used, giving rise to the so-called complex coacervate core micelles (C3Ms). In some mixtures, the formation of multiphase coacervates is observed when two polyelectrolytes of the same charge are mixed with another of opposite charge, normally forming complexes with different affinity. [1,2] This phenomenon raised great interest due to the presence of coacervates (including multiphasic ones) in living organisms and for their potential role in some diseases. We will report an investigation on the miscibility of coacervates formed by polymers and surfactants, in bulk and in the form of micelles. Our results confirm that surfactant systems that form mesophases (such as cetyltrimethylammonium in mixtures with polyacrylates) form two immiscible phases in bulk and, when prepared with block copolymers, appear as two populations of aggregates. However, by using another surfactant with shorter alkyl chain (decyltrimethyammonium) and by adding salt, we observe only a single bulk phase, but a wide distribution of aggregates. This finding stresses the importance of the liquid crystalline surfactant phase in defining miscibility. In another system, we have investigated the incorporation of a model enzyme into C3Ms as a means of producing nanoreactors. In this process, we have observed that, upon certain conditions, two populations of aggregates were formed. These systems were then investigated in bulk (using homopolymer instead of copolymer) and this study provided insights on how to formulate C3Ms with appropriate features.
[1] Lu, T. & Spruijt, E. Multiphase Complex Coacervate Droplets. J. Am. Chem. Soc. 142, 2905–2914 (2020).
[2] Queirós, M. V. A. & Loh, W. How to Predict the Order of Phase Separation of Polyelectrolyte Complexes and Their Miscibility. J. Phys. Chem. B 126, 5362–5373 (2022).
©fbpol2024 – Legals notices – Webdesign : chrisgaillard.com