Antimicrobial nanocomposites of hydroxyurethanes with inorganic acids

Abstract

Carbon dioxide (CO2) is the main greenhouse gas emitted through human activities, it is partially responsible for the global climate change, however, CO2 is considered a green carbon resource, making it an attractive raw material in industrial processes, such as monomers and solvents production in the polymer manufacture, especially polycarbonates. One of the most promising methodologies in this regard is the synthesis of cyclic carbonates via cycloaddition of CO2 in oxirane rings of organic epoxides. Our research group has investigated promising alternatives for the use of CO2, through its addition to bis-epoxides, notably diglycidyl ether-terminated poly(dimethylsiloxane) (PDMS), a silicone that can be used to build different types of structures. The presence of siloxane in the polymer chains results in high performance materials, that is, greater thermal stability, mechanical and chemical strengths. Nevertheless, materials with even more interesting properties can be obtained with the cycloaddition of polyepoxides, as is the case of epoxidized soybean oil (ESO), which additionally contributes to the scientific-technological advance of Brazilian raw materials, where Brazil is the 2nd largest producer of soybeans in the world. Aiming at the development of new products with differentiated properties, using Brazilian renewable sources, such as soybean oil, in this proposal we aim at the production of cyclocarnonates based on PDMS and soybean oil, the latter being our main raw material. It is also important to inform that OSE-PDMS systems, in addition to presenting advanced properties, will also cost considerably less than PDMS systems, being commercially attractive. Therefore, we aim to produce cyclocarbonates through CO2 fixation to obtain thermoset systems with attractive properties and cost. To the cyclocarbonates, amines will be added, producing hydroxyurethanes. Cyclocarbonate aminolysis is one of the most practical and environmentally safe strategies, as it enables the production of non-isocyanate polyurethanes (NIPU). Poly(hydroxyurethanes) are chemical products with high added value, and can be used in various economy sectors, from civil building, foams and adhesives, to the medical and dental device industry. Through the addition of reactive aminoalkoxysilanes, aminolysis can be used to combine poly(hydroxyurethanes) with silica and form the so-called urethanesils, with improved mechanical and thermal properties; in this project, we intend to add APTES and concomitantly adjust the length of the urethane chain and create covalently linked organosilicate domains (OSE-PDMSUr) within the material. Aminolysis can be potentiated by the addition of an inorganic acid, such as phosphotungstic acid (HPW) or phosphoric acid H3PO4, which can also confer bactericidal properties to OSE-PDMSUr. Therefore, in this work we will add HPW or H3PO4 acids to the reaction system , aiming at the production of antimicrobial films. Summing up, this project aims at the production of bactericidal films through the valorization of CO2 route and Brazilian renewable resources, specifically soybean oil, which will serve as raw material in the production of high performance thermoset poly(hydroxyurethanes), with bactericidal properties, better mechanical behavior, better thermal and chemical stabilities at lower cost. (AU)