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Collaboration between IQ-Unicamp and the Bayreuth University

Grant number: 14/26340-5
Support type:Research Grants - Visiting Researcher Grant - International
Duration: March 01, 2015 - March 15, 2015
Field of knowledge:Physical Sciences and Mathematics - Chemistry
Principal Investigator:Edvaldo Sabadini
Grantee:Edvaldo Sabadini
Visiting researcher: Heinz Hoffmann
Visiting researcher institution: University of Bayreuth, Germany
Home Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Collaboration between the groups of the IQ-Unicamp and Bayreuth University will be held with the visit of Professor Heinz Hoffmann in Brazil. During his visit we intent to develop rheological and calorimetric experiments involving giant micelles, which is a topic common for the two groups. Specifically, Professor Hoffmann has been investigated the formation of closed chains (rings and loops) of giant micelles constituted by C8F17SO3N(C2H5)4. Such structures were already verified through electronic microscopy obtained at cryogenic temperatures (Cryo-TEM). Probably, these structures should be responsible for the complex phenomenon associated with flow, ascribed as shear induced structures. This phenomenon is still unclear from the chemical point of view. Therefore, we are planning experiments with solutions of giant micelles formed by the surfactant C8F17SO3N(C2H5)4, in which the energy of the flow will be precisely determined in a rheometer. The effects of the flow will be investigated from the rheological and calorimetric viewpoints. The idea consist in shearing the solution for specify time in specific flow rates (measured with high precision) a then, obtain the variation of enthalpy (in an isothermal calorimeter, ITC) involved with the dilution (and destruction) of the giant micelles. The differences between the energies of systems non-sheared and sheared will be precisely determined and correlated with formation of closed structures. The effects of flow on structures of giant micelles have been intensively studied in the laboratory of IQ-Unicamp (Rodrigues, R.K.; da Silva, M. A.; Sabadini, E. Worm-like Micelles of CTAB and Sodium Salicylate under Turbulent Flow. Langmuir 2008, 24, 13875-13879. Rodrigues, R. K.; Ito, T. H.; Sabadini, E. Thermal-stability of mixed giant micelles of alkyltrimethylammonium surfactants and salicylate, J. Colloid Interf. Sci. 2011, 364, 407-412, 2011. During the two weeks of the visit of Professor Hoffmann, we will discussed about collaborative projects, which will involve the visit of students of the two groups in both laboratories. Additionally, Professor Hoffmann will present seminars in the Chemistry Institutes of Unicamp e USP and will visit LNLS in Campinas. (AU)