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Investigation about reversibility over electrostatic complexes formation in systems containing polymers and surfactants

Grant number: 18/09099-3
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): August 01, 2018
Effective date (End): February 28, 2021
Field of knowledge:Physical Sciences and Mathematics - Chemistry
Principal Investigator:Watson Loh
Grantee:Marcos Vinícius Aquino Queirós
Home Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
Associated research grant:15/25406-5 - Organizing matter: colloids formed by association of surfactants, polymers and nanoparticles, AP.TEM

Abstract

Complexation of polyelectrolytes with oppositely charged species in solution has been the focus of several researches regarding fundamental aspects and technological applications. These structures separate from the aqueous medium when they reach charge electroneutrality and can exist in two types of phases: the coacervates, characterized by being a concentrate, viscous liquid and the precipitates, which present as a fine solid. The components involved in the complexation are colloids ranging from homopolymers to block copolymers, polysaccharides, proteins, surfactants and inorganic nanoparticles. Its colloidal stability may depend on several factors, such as ionic strength, component charge density, polymer chain size, pH, etc. Furthermore, the formed aggregates may be outside the thermodynamic equilibrium, which implies that different preparation methodologies result in different colloidal properties, even if it is the same complex. Such behavior is still little understood and the lack of studies on the redispersion of these complexes induced by the presence of one of its own components serves as motivation for the development of this project. Based on this, it is intended to prepare binary complexes formed by the combination of polyelectrolytes and surfactant or other oppositely charged polyelectrolyte prepared by two different methods. Both homopolymers and block copolymers (ionic-neutral) will be used to monitor differences in the colloidal stability of the complexes. The main techniques employed to characterize the colloids will be light scattering, isothermal calorimetric titration and small angle X-ray scattering.