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采用辛胺疏水改性海藻酸钠合成了具有两亲性的高分子表面活性剂海藻酸辛酰胺(OAAD),并将其与SiO2纳米颗粒协同制备了稳定的Pickering乳液。通过FTIR、1HNMR、表面张力、荧光光谱、动态光散射、接触角测量、光学显微镜分别对OAAD、OAAD/SiO2纳米颗粒水分散体系和Pickering乳状液的性能进行了表征。结果表明,辛胺氨基成功接枝到海藻酸钠(SA)分子链上,OAAD界面张力较SA降低、临界聚集质量浓度为0.60 g/L,表现出良好的两亲性。将OAAD吸附在SiO2纳米颗粒表面形成的水分散体系用于稳定Pickering乳液时,发现随着OAAD质量浓度增加,SiO2纳米颗粒润湿性增加,Zeta电位减少,粒径增加;而乳液的粒径则逐渐减少,稳定性增强,其机理经初步分析为,当一定浓度的OAAD吸附在SiO2纳米颗粒表面,可导致颗粒间絮凝,从而在油水界面形成网络结构式界面膜,有利于提高Pickering乳液的稳定性。
An amphiphilic macromolecule surfactant, octyldiamide (OAAD), was synthesized by octylamine hydrophobically modified sodium alginate. A stable Pickering emulsion was prepared by synergistic reaction with SiO2 nanoparticles. The properties of OAAD, OAAD / SiO2 nanoparticle aqueous dispersion and Pickering emulsion were characterized by FTIR, 1HNMR, surface tension, fluorescence spectra, dynamic light scattering and contact angle measurement, respectively. The results showed that octylamino was successfully grafted onto the molecular chain of sodium alginate (SA), the interfacial tension of OAAD was lower than that of SA, and the critical mass concentration was 0.60 g / L, showing good amphiphilicity. When OAAD was adsorbed on the surface of SiO2 nanoparticle, the aqueous dispersion formed was used to stabilize Pickering emulsion. It was found that with the increase of OAAD concentration, the wettability of SiO2 nanoparticle increased, the Zeta potential decreased and the particle size increased. The mechanism of the OAAD adsorption on the surface of SiO2 nanoparticles can lead to the flocculation between the particles and the formation of a network structural interface membrane at the oil-water interface, which helps to improve the stability of the Pickering emulsion .