Otimização de polímeros carregados produzidos por polimerização via radical livre (PRL) e controlada (PRC, variante RAFT) para o aumento da viscosidade de suas soluções aquosas

Abstract

High viscosity polymeric solutions have applications ranging from the field of food industry (as thickeners) to the oil industry (as additives in drilling fluids used in oil extraction). Therefore, the seeking for polymeric materials more efficient to increase the viscosity of aqueous solution by the synthesis of new polymers with tailored molecular structure is justified by scientific and technologic reasons. Changing the structure parameters systematically, what can be accomplished today by Controlled Radical Polymerization techniques, may lead to more effective polymers to increase viscosity and, in the future, to the relationships between structure and that property. Such relationships are particularly more complicated for charged polymers in aqueous solutions. In this work, homopolymers of methacrylic acid and its copolymers with methacrylamide were synthesized by Reversible Addition-Fragmentation Chain Transfer (RAFT) and Free Radical Polymerization. The capacity to increase the viscosity of aqueous solution was tested for all materials. The analysis of viscosity data and the correlation to the polymers structure allowed the evaluation of the most important features to optimize such property. It has been found, as expected, that average molecular weight and composition (for copolymers) play a major role. In addition, the ionic strength on the viscosity was tested for the aqueous solutions and indicated that the addition of a neutral monomer (methacrylamide) made the solution viscosity less susceptible to salt, favoring the use of this kind of material at high ionic strengths, like sea water. Some materials have the potential to direct applications and the study was useful to advance in understanding the laws that govern the viscosity of polymeric aqueous solutions and the structure of the material, what can help in a more efficient way to obtain polymers for several applications.