Copolímeros de poliacrilamida parcialmente hidrolisada enxertada com poli(óxido de etileno-co-óxido de propileno) (HPAM-g-PEOPPO): síntese, caracterização e estudo de propriedades

Abstract

The objective of this work was to prepare and characterize thermoassociative copolymers of HPAM-g-PEOPPO, by grafting the poly(ethylene oxide-co-propylene oxide) – PEOPPO (EO/PO = 19/03) onto the backbone of a partially hydrolyzed polyacrylamide (HPAM). For this purpose, the copolymers were prepared in water by an amidation reaction between HPAM and PEOPPO, using EDC/NHS as condensing agents. Structural characterization was carried out through infrared (IR) and 1H NMR spectroscopy. Thermal stability on solid state was evaluated by thermogravimetric analysis (TGA). The evaluation of the properties in distilled water and on different concentrations of K2CO3 was made through ultraviolet-visible (UV-Vis) and rheological measurements. The characteristic functional groups peaks for all polymers were observed through infrared spectra. By 1H NMR spectra was possible to confirm that the copolymers were successfully synthesized and to determine the degree of grafting (0.9% for HPAM-g-PEOPPO1 and 2.4% for HPAM-g-PEOPPO2). TGA data demonstrated that copolymers have a different degradation steps in relation to HPAM. UVVis showed that HPAM did not exhibited change in transmittance with temperature for any of the aqueous media studied but their grafted derivatives showed a decrease in transmittance in the presence of salt. Rheological measurements showed that copolymers exhibited thermothickening behavior in saline media and higher apparent viscosity than HPAM above 70 °C. All results suggest HPAM-g-PEOPPO as an interesting candidate for enhanced oil recovery.