Synthesis And Aggregation Properties Of Sulfonic Amphiphilic Statistical Polymers

With the shortage of oil resources and the development of oil industry, heavy oil, which is about 30 % of the whole oil reserves, has become to be a very important part of oil product. The high viscosity (above 50 mPa·s) and density (above 0.943 g·cm_-3) can result in the low efficiency and high cost in the heavy oil's transportation process. There are physical and chemical technologies to reduce oil viscosity, and both of them have some demerit in application. Based on the work reported about oil viscosity reducing, amphiphilic polymer with special structure can form network aggregation and reduce oil viscosity dramatically. In this work, a method to synthesize amphiphilic random polymer was designed, and the aggregation behaviors of the polymers in solution were also investigated, thus the interaction mechanism between the polymers and heavy oil was also discussed by viscosity reducing of the polymers on the heavy oil.Three kinds of amphiphilic monomers, e.g., 2-(acrylamido)-octane sulfonic acid (AMC₈S), 2-(acrylamido)-dodecane sulfonic acid (AMC₁2S) and 2-(acrylamido)-hexadecane sulfonic acid (AMC₁6S) were synthesized by sulfonation using carbene, acrylonitrile and sulfuric acid. A novel series of amphiphilic random polymers were prepared by aqueous solution random polymerization between each monomer and 2-(acrylamido)-2-methylpropane- sulfonic acid (AMPS) with different mole fractions. Infrared spectroscopy, NMR spectroscopy, and elemental analysis indicated the structures of the amphiphilic monomers as (1), and the structures of amphiphilic polymers as (2).The aggregation behaviors of the polymers in aqueous solution were investigated by steady-state fluorescence, quasielastic light scattering and transmission electron microscopy. The amphiphilic polymers AMC₁2S with different mole fraction (x is 0.1, 0.3, and 0.5, respectively) were selected to investigate the effect of mole fraction on the association performance. The results showed that the critical aggregation concentration (cac) of the polymer significantly decreases with increasing of the mole fraction, and the aggregation mode transforms from intramolecular one to intermolecular one. The different amphiphilic polymers AMC₈S, AMC₁2S, AMC₁6S with same mole fraction (x = 0.1) were selected to study the alkyl chain length dependence on their association in aqueous solution. The investigation showed that the cac decreases dramatically with the increase of chain length, and the polymers tend to aggregate in intermolecular mode, leading to the formation of multimolecular aggregates.Three nonionic surfactants with different length of hydrophilic group were prepared by the reaction of C₁2H₂5OH and CH₂CH₂O, and the structures were identified by NMR and mass spectroscopy as HO(CH₂CH₂O)₁0C₁2H₂5 (C₁2E₁0), HO(CH₂CH₂O)₂0C₁2H₂5 (C₁2E₂0), and HO(CH₂CH₂O)₄0C₁2H₂5 (C₁2E₄0). The influence of surfactants on polymer aggregation performance was investigated, and the results showed that the polymer aggregates begin to collapse when the surfactant concentration reaches critical micell concentration (cmc) in the mixed solution. The destructive capability of surfactant increases with increasing the length of the hydrophilic group.Five kinds of amphiphilic polymer viscosity reducers (ICA) were synthesized using different quantities of AMC16S, which mostly undergo intermolecular association. The molecular weights and microstructures were investigated using scanning electron microscope and ubbelohde viscometer, and the results showed that the molecular weight and the compactness of microstructure both increase with the decreasing of AMC₁6S content. The viscosity reducing effect of ICA was investigated through Brookfield viscometer, and the viscosity-reducing rate, ion resistent ability and temperature resistent ability of ICA-2 are all ideal. The concentration needed to achieve 95 % viscosity reducing rate, the reducing interfacial tension ability, spreading effect on the surface of heavy oil, and multifying effect of ICA-2 and small molecular reducer (SJ) were investigated and compared. The results showed that the concentration of ICA-2 needed is much lower, and it has relatively weak reducing interfacial tension ability, better compatibility, and can emulsify the oil drops into little and better distributed ones. The interaction mechanisms with heavy oil of ICA and SJ were investigated, and the results showed that the better reducing effect of ICA is derived from the combination of interfacial file reparation, charge repulsion and steric hindrance against the reunion of oil drops, making ICA stronger to keep the maintenance of emulsion.