Effects of fluoroalkyl chain length and added moles of oxyethylene on aggregate formation of branched-tail fluorinated anionic surfactants

Abstract

The effects of fluorocarbon chain length and oxyethylene chain length were examined on the aggregate formation of newly synthesized double chain-type fluorinated anionic surfactants. The solution properties of double chain-type fluorinated anionic surfactants with two moles of added oxyethylene ( nFS(EO) 2) were found to depend on the fluorocarbon chain length. Thus, the Krafft temperature rose abruptly as the length of fluorocarbon chain increased, while the concentration at which the lowest surface tension is attained or aggregates are formed lowered with increasing chain length. In contrast, for double chain-type fluorinated anionic surfactants with two more moles of added oxyethylene ( nFS(EO) 4), their solution properties were almost inaffected by fluorocarbon chain length. That is, almost no change was seen in the concentration that indicates the lowest surface tension or aggregate formation when the chain length was altered, whereas the Krafft temperature was below 0°C for all members, providing them with a high solubility in water. In addition, spontaneous vesicle formation was observed in solution of nFS(EO) 4 and the size distribution of the vesicles thus formed had plural peaks (discrete size distribution).