双尾及多尾氟表面活性剂在有机溶剂中的表面活性研究

拟通过增加油溶性氟表面活性剂分子中碳氟链的数目,从而增大有机溶剂表面吸附层的碳氟链密度,以提高其降低有机溶剂表面张力的能力。合成了2个系列的氟表面活性剂:将全氟辛基磺酰氟与二胺(NH_2(CH_2)nNH_2,n=2,3,6,10)反应,合成以磺酰胺键为连接基、分子中含有2个碳氟链的油溶性氟表面活性剂;通过全氟辛酸与多元醇(乙二醇、1,2-丙二醇、丙三醇和季戊四醇)反应,合成以酯键为连接基、分子中分别含有2,3和4个碳氟链的油溶性氟表面活性剂。研究了这2个系列氟表面活性剂在乙醇、乙酸乙酯、丁酮以及乙醇-乙酸乙酯-丁酮三元混合溶剂中的表面活性,考察了氟表面活性剂分子结构、溶剂种类对表面活性的影响。结果显示,单纯增加碳氟链数目与降低表面张力之间不具有必然的依赖关系,分子整体构型也很重要,同时有机溶剂的种类对氟表面活性剂溶液的表面张力有显著影响。

Surface activities of double-tailed and multi-tailed fluorinated surfactants in organic solvents

This work attempts to reduce the surface tension of organic solvents with oil-soluble fluorinated surfactants. Number of fluorocarbon chains in the surfactant molecule is increased thus to enhance density of the fluorocarbon chains adsorbed on surface layer of the organic solvents. Two series of fluorinated surfactants were synthesized: through the reaction of perfluorooctane sulfonyl fluoride with diamine (NH2(CH2)nNH2, n=2, 3, 6, 10), the oil-soluble fluorinated surfactants containing sulfonyl amido group as the spacer, with two fluorocarbon chains in one surfactant molecule were obtained. Through the reaction of perfluorooctanoic acid with polyhydric alcohols (glycol, 1,2-propanediol, glycerol and pentaerythrite), the oil-soluble fluorinated surfactants, containing ester group as the spacer with two, three and four fluorocarbon chains in one surfactant molecule were obtained respectively. The surface activity of the two series of fluorinated surfactants in ethanol, ethyl acetate, butanone and the ternary mixed solvent of ethanol, ethyl acetate and butanone were studied. The effects of molecular structure of surfactants and the type of organic solvent on their surface activity were observed. The results showed that there was no simple inevitability between surface tension reduction and the number of fluorocarbon tails. The configuration of the whole molecule was also important, and the type of these polar organic solvents could have significant influences on the surface tension of such surfactant solution.