共轭亚油酸修饰Fe3O4纳米颗粒的刺激响应性

Stimuli-responsive Fe3O4 Nanoparticle Modified by Conjugated Linoleic Acid

采用少量天然不饱和脂肪酸共轭亚油酸(CLA)代替常用油酸对Fe3O4纳米颗粒进行表面修饰.通过引发CLA中共轭双键自交联增强表面修饰牢度,并利用该修饰层为修饰后的Fe3O4纳米颗粒提供第二重pH响应性.分别通过透射电子显微镜(TEM)表征粒径和形貌、全反射傅里叶变换红外光谱(ATR-FTIR)表征配位模式、热重(TG)分析修饰量、θ角表征表面润湿性、超景深三维显微技术表征修饰后颗粒稳定的Pickering乳液的粒径及分布等.结果表明,修饰后颗粒具有分散性好、修饰层薄而稳定、表面疏水性增强及具有明显的pH/磁双重响应性等特征.修饰后颗粒稳定的Pickering乳液具有乳化剂用量(质量分数0.05%)少、乳液为高内(油)相(体积分数80%)类型、pH响应能够开关乳液、外磁场驱使乳液定向移动等特征,且模拟实验显示借助该乳液可以有效实现水相有机污染物的萃取与分离.

The surface of Fe3O4 nanoparticles was modified by small dosage of the natural unsaturated fatty acid,conjugated linoleic acid(CLA),instead of oleic acid to prevent the nanoparticles from secondary agglomeration,oxidization and thus loss of magnetism,and to further improve thermal instability of the modified fatty acid layer.The stability of the modified layer was enhanced by means of self-crosslinking of conjugated double bond of CLA molecules,by which the modified particles could be responsive to the pH stimulus besides the magnetic stimulus.The size and morphology of the modified Fe3O4 NPs was imaged by TEM,the coordinationmodes by ATR-FTIR,the dosage of CLA by TG,the surface wettability byθangle analysis,moreover the droplet size and size distribution of Pickering emulsion stabilized by the modified particles were photographed by large-depth-of-field microscope.The experimental results indicated that the modified particles are welldispersed relying on a thin and stable,hydrophobic surface showing obvious dual pH/magnetic responsiveness.Pickering emulsion could be stabilized by small dosage of the modified particles(mass fraction 0.05%)and shown the emulsion characteristics of high internal oil phase(oil volume fraction 80%),switchable by a pH trigger,and migratable in an external magnetic field.A simulation experiment shows that the emulsion can effectively extract and separate organic pollutant in the aqueous phase.