Hyperbranched polymer composed of G1 polyamidoamine (PAMAM) and branched with poly (propylene oxide) (PPO)-block-poly (ethylene oxide) (PEO) was investigated to interact with sodium dodecyl sulfate (SDS) and di-dodecy...Hyperbranched polymer composed of G1 polyamidoamine (PAMAM) and branched with poly (propylene oxide) (PPO)-block-poly (ethylene oxide) (PEO) was investigated to interact with sodium dodecyl sulfate (SDS) and di-dodecyl dimethyl ammonium bromide (DDAB), respectively, by the methods of turbidity titration and analysis, rheology measurements, dynamic light scattering (DLS) and transmission electron microscopy (TEM). It was noticeable that even at extremely low concentration of SDS (even far from the critical micelle concentration (cmc)), the system exhibits high turbidity, indicating that SDS molecules can insert into cationic amine groups and hydrophobic microenvironment, resulting in the formation of polymer-SDS complexes with large size. At the SDS concentration range of below 0.1 mM, the turbidity and cloud point (CP) temperature of the system keep almost invariable, mostly because of the repulsion between SDS molecules and the complexes. And, therefore, the size of the mixed aggregates retains almost constant. In the case of vesicle system of DDAB, the aggregates are in the size of 100 nm - 200 nm and 500 nm - 3000 nm at the concentrations of 30 mM and 100 mM, respectively. However, in the mixture of hyperbranched polymer with DDAB, by comparison, the size is smaller in a binary system than that of in DDAB system. So it is reasonable to infer that DDAB molecules remove from multilamellar vesicles of DDAB to the hydrophobic microenvironment of hyperbranched polymer aggregates, with the addition of the hyperbranched polymer. It leads to the destruction of the gel-like conformation in DDAB system, leading to the shear thinning of the mixture and, as a result, the viscoelastic character of the system is lost in a large degree.展开更多
油藏岩石表面油-水润湿性对原油的开采具有重要影响,润湿性向亲水转变被认为是低矿化度水驱技术的主要机制,但是低矿化度水注入后岩石表面发生润湿性转变的微观机理目前依然存在很多争议.本研究针对极性分子在岩石表面的极性吸附,研究...油藏岩石表面油-水润湿性对原油的开采具有重要影响,润湿性向亲水转变被认为是低矿化度水驱技术的主要机制,但是低矿化度水注入后岩石表面发生润湿性转变的微观机理目前依然存在很多争议.本研究针对极性分子在岩石表面的极性吸附,研究水中无机盐离子对石英表面润湿性的影响及其作用机理.研究发现,相同浓度下,NaCl溶液和KCl溶液的接触角基本相同;在浓度较低时,CaCl2溶液使三相接触角降低的幅度比NaCl溶液更大,Na2SO4溶液比NaCl溶液效果更明显;在较高浓度下,Na2SO4溶液的接触角与NaCl溶液相似.当离子浓度大到一定程度时,不同溶液的接触角都趋于15°左右,离子使吸附的极性分子基本都脱附,导致石英表面润湿性向亲水转变.基于石英粉末的Zeta电位测量和石英片表面的原子力显微镜(atomic force microscopy,AFM)粗糙度分析,提出了两种机理解释:(1)癸烷中的十八胺在油水界面质子化带正电,与水中阴离子相互吸引,降低了油水界面张力;(2)水中的阳离子在带负电的石英表面吸附,使石英片表面负电性减弱,并置换了部分石英表面吸附的十八胺分子,使石英表面亲油性减弱.展开更多
文摘Hyperbranched polymer composed of G1 polyamidoamine (PAMAM) and branched with poly (propylene oxide) (PPO)-block-poly (ethylene oxide) (PEO) was investigated to interact with sodium dodecyl sulfate (SDS) and di-dodecyl dimethyl ammonium bromide (DDAB), respectively, by the methods of turbidity titration and analysis, rheology measurements, dynamic light scattering (DLS) and transmission electron microscopy (TEM). It was noticeable that even at extremely low concentration of SDS (even far from the critical micelle concentration (cmc)), the system exhibits high turbidity, indicating that SDS molecules can insert into cationic amine groups and hydrophobic microenvironment, resulting in the formation of polymer-SDS complexes with large size. At the SDS concentration range of below 0.1 mM, the turbidity and cloud point (CP) temperature of the system keep almost invariable, mostly because of the repulsion between SDS molecules and the complexes. And, therefore, the size of the mixed aggregates retains almost constant. In the case of vesicle system of DDAB, the aggregates are in the size of 100 nm - 200 nm and 500 nm - 3000 nm at the concentrations of 30 mM and 100 mM, respectively. However, in the mixture of hyperbranched polymer with DDAB, by comparison, the size is smaller in a binary system than that of in DDAB system. So it is reasonable to infer that DDAB molecules remove from multilamellar vesicles of DDAB to the hydrophobic microenvironment of hyperbranched polymer aggregates, with the addition of the hyperbranched polymer. It leads to the destruction of the gel-like conformation in DDAB system, leading to the shear thinning of the mixture and, as a result, the viscoelastic character of the system is lost in a large degree.
文摘油藏岩石表面油-水润湿性对原油的开采具有重要影响,润湿性向亲水转变被认为是低矿化度水驱技术的主要机制,但是低矿化度水注入后岩石表面发生润湿性转变的微观机理目前依然存在很多争议.本研究针对极性分子在岩石表面的极性吸附,研究水中无机盐离子对石英表面润湿性的影响及其作用机理.研究发现,相同浓度下,NaCl溶液和KCl溶液的接触角基本相同;在浓度较低时,CaCl2溶液使三相接触角降低的幅度比NaCl溶液更大,Na2SO4溶液比NaCl溶液效果更明显;在较高浓度下,Na2SO4溶液的接触角与NaCl溶液相似.当离子浓度大到一定程度时,不同溶液的接触角都趋于15°左右,离子使吸附的极性分子基本都脱附,导致石英表面润湿性向亲水转变.基于石英粉末的Zeta电位测量和石英片表面的原子力显微镜(atomic force microscopy,AFM)粗糙度分析,提出了两种机理解释:(1)癸烷中的十八胺在油水界面质子化带正电,与水中阴离子相互吸引,降低了油水界面张力;(2)水中的阳离子在带负电的石英表面吸附,使石英片表面负电性减弱,并置换了部分石英表面吸附的十八胺分子,使石英表面亲油性减弱.
