Surfactants reactive

Another approach to producing latexes with chemically bound surface-active groups is to use a reactive surfactant—a surfactant with a polymerizable double bond, such as sodium dodecyl allyl sulfosuccinate [Wang et al., 2001a,b,c]. Copolymerization of the reactive surfactant with the monomer of interest binds the surface active groups into the polymer chains. 

Compared to micellar bimolecular reactions involving reactive surfactant counterions, considerably less work has been done on micellar bimolecular reactions involving two neutral reactants. We will discuss here micellar effects on cycloaddition reactions though this is by no means the only system for which micellar catalysis has been investigated (see, e.g., Bonollo et al. °). 

A reactive surfactant shown next (RS) was used as a comonomer in a seeded polymerization. RS was easily adsorbed on seed particles due to their amphiphilicity. If dialkyl fumarate was preabsorbed in the particle, the polymerization proceeded quickly and resulted in the formation of skin layer of RS-fumarate copolymer. Because the vinyl group in RS is an allyl type, RS in aqueous phase hardly polymerizes and no water-soluble homopolymer was formed. The active ester group of RS on the skin layer was used for the preparation of functional microspheres (18). 

In copolymerization of styrene, more monodisperse and smaller-size particles were obtained with the PEO-MA macromonomer with a longer alkylene spacer group, thus indicating their effectiveness as reactive surfactant increases in the series [71]... 

Guyot, A. and Tauer, K. Reactive Surfactants in Emulsion Polymerization.Vol. Ill,pp.43-66. 

A Diels-Alder adduct, an example of reactive surfactants, has been synthesized from linoleic acid and maleic anhydride, according to Scheme 13.1, and used for preparing nanosized Mg(OH)2 (MH) [12]. 

Marosi, G., Marton, A., Csontos, I., Matko, S., Szep, A., Anna, P., Bertalan, G., and Kiss, E. 2004. Reactive surfactants—New type of additive for multicomponent polymer systems. From Colloids to Nanotechnology 125 189-93. 

In some areas, for example in crop protection, moving away from solvents simply required the development of new forms of delivery, e.g. concentrated emulsions or suspo-emulsions progressively displaced the emulsifiable concentrates. A change in the surfactant system was obviously necessary, but the new formulations could be made using commercially available products. In other instances, for example in the field of emulsion polymers, new colloidal species were developed and are still the subject of extensive research the reactive surfactants. 

Reactive surfactants can covalently bind to the dispersed phase and as such have a distinct advantage over conventional surfactants that are only physically adsorbed and can be displaced from the interface by shear or phase changes with the subsequent loss of emulsion stability. Furthermore, if the substrate is coalesced to produce decorative or protective films, the desorption can result in, e.g. reduced adhesion, increased water sensitivity and modification of the hardness, barrier and optical properties of the film. 

Reactive surfactants have also economic and environmental advantages. The binding to the dispersed phase makes these surfactants an integral part of the finished product and enhances the yield in active matter on a weight basis. It furthermore prevents the release of surfactants in the water effluents on production and application and, as such, reduces the environmental impact of intermediate products and commercial formulations. 

Depending upon the chemical structure and effects, there are different types of reactive surfactants ... 

Most of the reactive surfactants used for emulsion polymerization have the reactive group at the end of the hydrophobic moiety of the molecule, on the assumption that the polymerization process takes place in the latex particle. Work of Ferguson et al. [14] shows indeed a lower stability of lattices produced with Surfmers with an acrylate group attached to the end of the hydrophilic chain than those produced with the equivalent terminated with an ethyl ester group. 

The concept of using reactive surfactants in emulsion polymerization processes is relatively recent and aims at eliminating the drawbacks associated with the use of conventional, monomeric, nonreactive surfactants. Despite the demonstrated advantages and the availability of commercial products, reactive surfactants have not yet reached a widespread... 

Monteiro, M.J., Brussels, R. and Wilkinson, T.S. (2001) Emulsion polymerization of methyl methacrylate in the presence of novel addition-fragmentation chain-transfer reactive surfactant (transurf). /. Polym. Sci., A 39,2813-20. 

Schoonbrood, H.A.S., Unzue, MJ., Beck, O. and Asua, J.M. (1997) Reactive surfactants in heterophase polymerization. 7. Emulsion copolymerization mechanism involving three anionic polymerizable surfactants (surfmers) with styrene-butyl acrylate acrylic acid. Macromolecules, 30, 6024-33. 

Sindt, O., Gauthier, C., Hamaide, T. and Guyot, AJ. (2000) Reactive surfactants in heterophase polymerization. XVI. Emulsion copolymerization of styrene-butyl acrylate-acrylic acid in the presence of simple maleate reactive surfactants. /. Appl. Polym. Sci, 77,2768-76. 

Aramendia, E., Mallegol, J., Jeynes, C., Barandiaran, M.J., Keddie, J.L. and Asua, J.M. (2003) Distribution of surfactants near acrylic latex film surfaces A comparison of conventional and reactive surfactants (surfmers). Langmuir, 19, 3212-21. 

Dufour,M.G. andGuyot,A. (2003) Nonionic reactive surfactants. I. Synthesis andcharacterization. Colloid Polym. Sci., 281, 97-104. 

Asua, J.M and Schoonbrood, H.A.S. (1998) Reactive surfactants in heterophase polymerisation. Acta Polymerica, 49, 671-86. 

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