Surfactants, overview defined

The homologues of the methylated non-ionic EO/PO surfactant blend were ionised as [M + NH4]+ ions. A mixture of these isomeric compounds, which could not be defined by their structure because separation was impossible, was ionised with its [M + NH4]+ ion at m/z 568. The mixture of different ions hidden behind this defined m/z ratio was submitted to fragmentation by the application of APCI—FIA—MS— MS(+). The product ion spectrum of the selected isomer as shown with its structure in Fig. 2.9.23 is presented together with the interpretation of the fragmentation behaviour of the isomer. One of the main difficulties that complicated the determination of the structure was that one EO unit in the ethoxylate chain in combination with an additional methylene group in the alkyl chain is equivalent to one PO unit in the ethoxylate chain (cf. table of structural combinations). The overview spectrum of the blend was complex because of this variation in homologues and isomers. The product ion spectrum was also complex, because product ions obtained by FIA from isomers with different EO/PO sequences could be observed complicating the spectrum. The statistical variations of the EO and PO units in the ethoxylate chain of the parent ions of isomers with m/z 568 under CID... 

It has been recognised for some time (see for example reference 1), that surfactants can increase the rate and extent of transport of solute molecules through biological membranes by fluidisation of the membrane. It is only recently, however, that sufficient work has been carried out to allow some analysis of structure-action relationships. In this overview an attempt is made, by reference to our own work and to work in the literature, to define those structural features in polyoxyethylene alkyl and aryl ethers which give rise to biological activity, especially as it is manifested in interactions with biomembranes and subsequent increase in the transport of drug molecules. 

From this overview and from Hadjichristidis et al. [ 13] recently published book, it is evident that amphiphilic block and graft copolymers are an interesting class of polymeric surfactants. They are unique is that they self-assemble into nanoparticles with well-defined sizes and morphologies. 

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