TOF SIMS STUDY OF THE DESORPTION OF EMULSIFIERS FROM POLYSTYRENE LATEXES

The desorption of emulsifiers from the particle surface of polystyrene latexes prepared by emulsion polymerization has been studied by Time- of-Flight Secondary Ion Mass Spectrometry (ToF SIMS). Two polystyrene latexes prepared with respectively sodium dodecyl sulphate and sodium dodecylbenzene sulphonate as emulsifiers were compared. It has been sh own that the quasi-molecular, parent ions and the characteristic fragm ents of the emulsifiers can easily be observed in positive and negativ e ToF SIMS. But these ions are more sensitive in the negative mode. Th e results have shown that after extensive purification with mixed-bed ion-exchange resins, the emulsifier was totally absent on the latex pr epared with sodium dodecyl sulphate and that only traces of the emulsi fier exist on the latex prepared with sodium dodecylbenzene sulphonate . These results suggest that strong acid emulsifiers can be desorbed b y mixed-bed ion-exchange resins.