Study On Preparation And Swelling Properties Of Copolymer Microgels

Linear polyacrylamide polymers were widely uesd as water plugging and profile control agent in main oil fields in China. But they had poor temperature-resistance and salt-resistance. Exploring a novel polymer with favorable temperature-resistance and salt-resistance properties was significantly important both in theory and in application.In this paper, a series of P(AM-co-AN) microgels were prepared by dispersion copolymerization of hydrophilic monomer acrylamide (AM) and hydrophobic monomer acrylontrile (AN) using azobisisobutyronitrile (AIBN) as initiator, N,N'-methylenebisacrylamide (Bis-A) as cross-linker and polyvinylpyrrolidon (PVP K-30) as stabilizer in an aqueous alcoholic media which showed good swelling properties. The influences of copolymerization conditions on the reaction conversion rate and the average particle size of P(AM-co-AN) microgels were investigated respectively, and the average particle size of microgels was controlled in the range of 0.63 to 1.82μm. The effect of AM/AN mass ratio on the morphology and thermal properties of the microgels was also investigated by scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). It was found that the size distributions of the microgels became more monodispersed and the thermal properties of the microgels was enhanced by increasing the content of AN comonomer so that they could be used at higher temperature.In order to study the effect of comonomers on the properties of the microgels further, P(AM-co-AMPS) and P(AM-co-AN-co-AMPS) microgels were synthesized by dispersion copolymerization using AM as main monomer, AN and 2-acrylamido-2- methylpropanesulfonic acid (AMPS) as comonomers, 2,2'-azobis[2-(2-imidazolin- 2-yl)propane] dihydrochloride (VA-044), Bis-A and PVP K-30 as initiator, cross-linker and dispersion stabilizer. The result indicated that the copolymer microgels showed good swelling properties, temperature-resistance and salt-resistance properties, and they may be used as water plugging material in oil exploitation.Copolymer microgels with narrow size distribution were prepared by dispersion copolymerization. The synthesized copolymer micrgels kept spherical structure and their sizes could be controlled by changing reaction parameters. Temperature-resistance and salt-resistance performances of microgels were improved by adding the comonomers, so that they could be used as water plugging and profile control agent in complex conditions in oil exploration.