Polymerizable fluorinated surfactants

Polymerizable surfactants can be used to modify surfaces by polymerization of the adsorbed surfactant by ultraviolet (UV) irradiation. A surface of a paint film or lacquer can be fluorinated by cross linking a polymerizable fluorinated surfactant which has migrated to the surface and formed a monolayer [231]. 

Fig. 8.1 Effect of fluorinated surfactants on the wettability of a poly(methyl methacrylate) lacquer film (i) polymerizable surfactant (ii) nonreactive surfactant (iii) fluorinated polymer. (Reproduced with permission from Ref. 47. Copyright 1998 by Wiley-Chichester.)...

The effect of polymerization has been demonstrated with two fluorinated surfactants, one polymerizable and one nonreactive, added to polyCmethyl-methacrylate) lacquer. After curing, the films were rinsed with a solvent. Contact-angle measurements (Fig. 8.1) [47,49] showed that the film containing the polymerizable surfactant (i) had been permanently hydrophobized, whereas the nonreactive surfactant (ii) had been washed away. A preformed polymer (iii) also gave a permanently hydrophobic surface. 

The hydrophobic monomers styrene and MMA were copolymerized with the sodium salt of vinylbenzylsulfosuccinic acid as a polymerizable surfactant grafting of the surfactant onto the particles was estimated to be about 50-75% [51]. A polymerizable surfactant was formed by the esterification of hydroxypropylmethacrylate or hydroxyethyhnethacrylate with succinic anhydride [53]. However, in addition to the surfmer, sodium dodecyl sulfate (SDS) was employed to provide a sufficient stability to the latexes. A mono-fluorooctyl maleate surfactant was used to stabilize the polymerization of styrene in miniemulsion [55]. Although the polymerizable moiety was not fixed at the end of the fluorinated chain (the hydrophobe part), the surfactant could be copolymerized with the styrene monomer. Subsequently, on comparison of the infrared (IR) spectra (vibration of -CF2 and -CFj) before and after dialysis, it was estimated that 92% of the surfactant had remained grafted post-dialysis. 

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