Abstract: Recently, high molecular weight additives such as proteins or synthetic polymer have been dissolved in water pools in W/O microemulsions, which served as microreacter for enzymatic or chemical reactions. However, the report on the effect of different molecular weight polymers on the state of water in W/O microemulsions made with zwitterionic surfactant has been so far scarcely investigated. 　　We report here the results of research concerning the effect of different molecular weight polyvinylpyrrolidones(PVPK15, PVPK30, PVPK90, and PVPK120) on the state of water in two kinds W/O microemulsions made with water/dodecyl betaine (C12BE)/npentanol(C5OH)/nheptane (C7H16) (I), and water/ aerosol OT (AOT)/C7H16(Ⅱ) using Fourier Transform Infrared(FTIR) spetroscopy. 　　 FTIR spectra of all the samples were taken on a BIORED model 165 FTIR spectrometer using AgCl cells of a fixed path length of 0.025 nm. All spectra were recorded at room temperature (25 ℃). Two kinds of W/O microemulsions with PVP that the changes in the OH stretch peak of water molecule could be observed. The results indicate that the content of the bound water was increased, and the amount of the bulk water was decreased in the system (I)in the presence of the PVP. But the amount of bound water was decreased and the amount of the bulk water was increased in the system(Ⅱ) as PVP was added. This is contributed to the interaction of PVP macromolecules with the head groups of amphiphile: the polarity of C12BE molecule was increased but the polarity of AOT molecule was decreased as PVP was added.

Key words: FTIR, Polyvinylpyrrolidone(PVP), Dodecyl betaine(C12BE), Sodium