海藻酸辛酰胺的制备及其协同氨基SiO2纳米粒稳定液体石蜡/水乳液的研究

以辛胺为疏水改性剂,采用酰化法制得具有两亲性的海藻酸辛酰胺(ACA)。将ACA与采用修正Stber法制备的氨基二氧化硅(SiO_2-NH_2)纳米粒混合,在超声的作用下制得O/W型Pickering乳液。通过FT-IR,~1H NMR和荧光光谱对ACA的结构和性能进行表征。并采用激光粒度和Zeta电位分析仪、接触角测量仪和光学显微镜探究了ACA,SiO_2-NH_2及其协同水分散体系的胶体性能和相应的Pickering乳液的形貌。结果表明:ACA的取代度为0.29,在0.15 mol/L Na Cl水溶液中的临界聚集浓度(cac)为0.42 g/L,表现出较强的两亲性能。ACA通过静电作用力成功地吸附于SiO_2-NH_2纳米粒上,使水动力学粒径只有155 nm的SiO_2-NH_2纳米粒增长至386 nm,Zeta电位由+22.2 mV转变为-30.7 mV,在水溶液中能够表现出良好的稳定性。吸附于SiO_2-NH_2纳米粒表面的ACA可以抑制无机纳米粒的聚沉,而游离的ACA形成的胶束结构的疏水内腔能够增溶油滴,减少小油滴的聚并。光学显微镜中出现了粒径较大的Pickering乳液液滴和粒径较小的传统乳液液滴共存的现象,当ACA质量浓度在0.5 cac~1.0 cac时,2种乳液共存现象最为显著。

Preparation of alginate caprylamide and its function for stabilizing liquid paraffin/water emulsions in cooperation with amino-silica nanoparticles

Amphiphilic alginate caprylamide (ACA) was prepared via the amidation using the octylamine as a hydrophobic modifier. Then, O/W Pickering emulsions were prepared by mixing ACA with SiO2-NH2 nanoparticles formed by modified Stöber method under the action of ultrasonic wave. The structure and performance of ACA were characterized by FT-IR, 1H NMR and fluorescence spectrum. The colloidal performance of ACA, SiO2-NH2 and their synergistic water dispersion system, as well as the morphology of the corresponding Pickering emulsions were investigated by the means of laser particle size and Zeta potential analyzer, contact angle meter and optical microscope. Experimental results showed that ACA with the degree of substitution of 0.29, exhibits good amphiphilic properties with the critical aggregation concentration (cac) of 0.42 g/L in 0.15 mol/L aqueous NaCl solution. ACA is successfully adsorbed on the surface of SiO2-NH2 nanoparticles via electrostatic force, causing the hydrodynamic size of SiO2-NH2 increases from 155 nm to 386 nm, and the Zeta potential of SiO2-NH2 changes from +22.2 mV to -30.7 mV, which can exhibit good stabilizing performance in aqueous solution. ACA absorbed on the surface of SiO2-NH2 nanoparticles can inhibit the aggregation and settlement of inorganic nanoparticles while the hydrophobic cavity of the micelle structure formed by free ACA can solubilize the oil droplets, reduce the coalescence of small oil droplets. The co-existence of larger Pickering emulsion droplets and smaller traditional emulsion droplets appear in the optical microscope images. When the mass concentration of ACA is in the range of 0.5 cac-1.0 cac, the co-existence of the two kinds of emulsions is the most obvious phenomenon.