Preparation and Characterization of Temperature-Responsive Polymeric Surfactants

Abstract

Canada has large reserves of heavy oil stored in the form of oil sands in the Athabasca region. This type of heavy oil does not flow at room temperature and its agglomeration with sand complicates its extraction. Consequently, extraction of the oil is costly and remains challenging. This project aims to use a temperature-responsive polymeric surfactant (TRPS) to improve the extraction of oil. The temperature-responsive polymeric surfactant (TRPS) poly(ethylene glycol)-b-poly[2-(2-methoxyethoxy) ethyl methacrylate] (PEG-b-PMEO2MA) was successfully prepared by atom transfer radical polymerization (ATRP) and its efficacy at extracting oil from oil sands was investigated. First, several PEG-b-PMEO2MA samples were synthesized having an absolute molecular weight ranging from 17,000 to 20,000 g/mol as determined by NMR and an apparent PDI ranging from 1.1 to 1.5 as determined by GPC analysis. Then, the lower critical solution temperature (LCST) was found to equal 34 ± 1°C for all samples by turbidity measurements. The PEG113-b-PMEO2MA64 micelles in aqueous solution, whose hydrodynamic diameter (dh) determined by dynamic light scattering (DLS) equaled 26.3 ± 0.3 nm, had an aggregation number (Nagg) of 100 ± 8. After characterization of this TRPS, PEG-b-PMEO2MA was used for oil extraction and showed promising results. With the addition of 60 to 65 mg of toluene on top of 15 mL of a 1 mg/mL PEG-b-PMEO2MA aqueous solution, complete oil recovery could be achieved by putting the TRPS solution with 1 g of oil sands in a shaker at 45 or 50 ºC for 24 hrs. In addition, a time-dependent oil extraction experiment showed that by using a 1 mg/mL TRPS aqueous solution, 100% oil recovery was reached after only 6 hrs. Furthermore, the PEG-b-PMEO2MA aqueous solution could be recycled for several oil extraction cycles while still maintaining a high oil recovery.