Fluorosilicone surfactants, surface tension

Table IX Aqueous-Solution Surface Tension (ff soin) of Fluorosilicone Surfactants...

The latest class of silicone surfactants to be prepared are the fluorosilicone copolymers (73,74). These compounds combine disiloxane or branched trisiloxane structures modified with fiuoroalkyl radicals as the hydrophobic moiety and polyethylene oxide units as the hydrophilic group. Two copolymers containing different fiuoroalkyl groups have been reported for use in shampoo systems. The materials containing 3,3,3, trifluoropropyl units were characterized by surface tensions approximately equivalent to dimethicone fluids ( 20.1 mN/m), while polymers containing 3,3,4,4,5,5,6,6,6, nonafluorohexyl groups displayed surface tensions as low as 17.6 mN/m (75). 

To increase the surface activity, Owen and Groh [135] increased the fluorocarbon content of the side chains while maintaining the ethylene link between the fluorocarbon group and the silicon atom. Nonafluorohexyl (3,3,4,4,5,5,6,6,6-nonafluorohexyl) disiloxane and trisiloxane surfactants have equilibrium surface tensions in water at the cmc of 20 niN/m [142]. However, the response of their surface tension to dynamic changes is impeded by bulkiness of the flouroalkyl group [142]. The surface tension of the fluorosilicones is shown in Table 1.8. 

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