干水法制备核壳聚合物微球及其性能评价

Preparation and properties of core-shell polymer microspheres by dry water method

摘要:

以疏水SiO2、单体、引发剂和交联剂为原料，水为溶剂，采用干水法制备核壳聚合物微球PMS@SiO2，分别考察了SiO2疏水性、硅水质量比、搅拌速度和搅拌时间对形成稳定干水微反应器的影响。以过硫酸铵和亚硫酸氢钠为引发剂，N,N'-亚甲基双丙烯酰胺为交联剂，通过正交实验对内核水相发生聚合反应的条件进行了优化。采用傅里叶变换红外光谱仪、热重分析仪、激光粒度仪、扫描电子显微镜和透射电子显微镜对微球的化学结构、热稳定性及微观形貌进行了表征，评价了微球的吸水膨胀性能和调驱性能。结果表明，核壳聚合物微球PMS@SiO2的最佳制备条件为：SiO2-R812S与水相质量比1∶10，搅拌速度12000 r/min，搅拌时间120 s，交联剂用量0.1%（以单体总质量为基准，下同），引发剂用量0.15%，反应温度50 ℃，反应时间4 h。与常规聚合物微球PMS相比，该微球在90 ℃环境中水化20 d，膨胀倍数约为5.0，具有缓膨特性。物模调驱实验结果表明，PMS@SiO2的封堵率达90.39%，残余阻力系数为10.409，采收率增幅可达34.02%。与PMS相比，其采收率提高了11.89%，具备良好的调驱性能。

Abstract:

The core-shell polymer microspheres PMS@SiO2 were prepared by dry water method using hydrophobic SiO2 and aqueous phase containing monomer, initiator ,crosslinking agent and water. The effects of SiO2 hydrophobicity, the ratio of silicon and water, stirring speed and stirring time on the formation of stable dry water microreactor were investigated. The polymerization conditions of core water phase were optimized by orthogonal experiment, in which ammonium persulfate and sodium bisulfite were used as initiators ,N,N'-methylene bisacrylamide was served as a crosslinking agent. The chemical structure, thermal stability and microscopic appearance of the microspheres were respectively characterized by Fourier transform infrared spectroscopy(FTIR), thermogravimetric analyzer(TGA), laser particle size analyzer, scanning electron microscope (SEM) and transmission electron microscope(TEM), its water swelling and flooding performance were also evaluated. The results showed that the best preparation condition of core-shell polymer microspheres PMS@SiO2 were as follows: the mass ratio of SiO2-R812S and water phase was 1:10, the stirring speed and stirring time were respectively 12,000 r/min and 120 s, the amount of crosslinking agent and initiators were respectively 0.1% and 0.15%, the reaction temperature was 50 ℃ and the reaction time was 4 h. The microspheres were hydrated at 90 ℃ for 20 days, and its expansion times was about 5.0. Compared with the conventional polymer microspheres PMS, PMS@SiO2 showed slower expansion. The results of physical model displacement experiment indicated that the plugging ratio of PMS@SiO2 could reach 90.39%, the residual resistance coefficient was 10.409, and the recovery rate can be increased by 34.02%. The recovery rate of PMS@SiO2 was 11.89% higher than that of PMS, with good profile control and displacement performance.