静电作用构筑的新型表面活性剂及其性能

Preparation and properties of a novel surfactant constructed by electrostatic interactions

以硬脂酸为原料,合成了长碳链的N-(2-(二甲基氨基)乙基)硬脂酰胺(C18N2N)。将C18N2N与天然有机酸肉桂酸(TA)按一定比例复配,即可得到一种新型表面活性剂。该表面活性剂通过非共价键的静电相互作用而形成,省去了繁琐的合成步骤。通过表面张力仪和流变仪测试了该表面活性剂的表面活性和流变性能,结果表明该表面活性剂的临界胶束浓度和γ_(cmc)分别为0.11 mmol/L和32.4 mN/m,表现出很强的聚集和吸附能力。在浓度为25 mmol/L时,该表面活性剂即可形成蠕虫状胶束,形成的黏弹溶液具有较好的耐温耐剪切性能。还考查了该新型表面活性剂作为压裂液的应用性质,发现该新型表面活性剂还具有优良的携砂性能,沉降速率仅为0.26 cm/min。该表面活性剂制备简单,性能优良,拓展了新型表面活性剂的制备方法和应用范围。

Taking stearic acid as the raw material,N-(2-(dimethylamino)ethyl)stearamide(C18N2N)was synthesized.A new surfactant was prepared by mixing C18N2N and cinnamic acid(TA)with fixed ratio.This surfactant was formed by noncovalent electrostatic interactions,which avoided complicated synthetic procedures.The surface activity and rheological properties of the surfactant were investigated with a surface tensiometer and a rheometer.The critical micelle concentration(cmc)and the surface tension at cmc(γ_(cmc))of the surfactant were 0.11 mmol/L and 32.4 mN/m,indicative of strong aggregation and adsorption ability.The maximum amount adsorbed(Γ_(max))and the minimum molecular area occupied(A_(min))were 2.77μmol/m^(2) and 0.6 nm^(2).Wormlike micelles were formed at the concentration of 25 mmol/L.When the concentration was over 100 mmol/L,the zero-shear viscosity(η_(0))abruptly increased and then reached the maximum value for the surfactant of C18N2N/TA containing 150 mmol/L TA.The solution viscosity was as high as 1761.38 Pa·s.The effects of temperature on the rheological behavior were also considered.With the increase of temperature,the viscosity gradually increased.And when the temperature reached 40℃,η_(0) of the solution with the concentration of 100 mmol/L achieved the maximum value of 1370.386 Pa·s.When the temperature continued to rise,η_(0) began to decrease with further increasing temperature.A remarkable viscosity of 305.55 Pa·s was still remained at 50℃.The viscoelastic solutions showed good temperature resistance and shear resistance.The surfactant solutions applied as the fracturing fluid were also investigated.This surfactant also showed excellent sand-carrying performance,and the settling rate of the sand was merely 0.26 cm/min.This surfactant could be simply prepared and showed excellent performance,which expanded the preparation and application field of novel surfactants.