Research On The Interactions Between Surfactants And Polymers And Their Effects To The Middle-phase Microemulsion

Surfactants and polymers are widely used in many industry, such as water treatment, enhanced oil recovery and so on. Investigation on the interaction between surfactants and polymers is of great importance to both pure and applied science. In addition, for microemulsion, especially the middle-phase microemulsion, is thermodynamically stable, transparent and has the ultralow interfacial tension, more and more attentions have been paid on many areas (such as enhanced oil recovery and so on). Considering the special phenomena in surfactant and polymer mixture, the effect of interaction of surfactant and polymer on the middle-phase microemulsions is desired. The main contents and the results are listed as followings:(l)The interfacial tension measurement showed that the interfacial tension between DTAB and 1-heptane has a turning point at CMC; on the addition of PAM, the interfacial tension between the mixture of DTAB/PAM and 1-heptane has a sharp decrease, the turning point occurred at the concentration below CMC then the interfacial tension began to increase; on the addition of HMPAM, the interfacial tension between the mixture of DTAB/HMPAM and 1-heptane has a little decrease and the turning point occurred at CMC and after CMC, the interfacial tension almost keep fixed. The result indicates that there is a intensity interaction between DTAB and PAM.(2) The interfacial tension measurement has been used to study the interfacial tension and its dynamic process between Gemini and 1-heptane. The phenomeno is very special. The interfacial tension between Gemini and 1-heptane has a lowest point. And the time when the interfacial tension between Gemini and 1-heptane on the addition of HMPAM becomes very long. All of these phenomena still need to be studied.(3) The fluorescence measurements showed that the values of I1/I3 decreases with the increase of concentration of DTAB and at CMC the micro-environment decreased a lot. After addition of PAM/HMPAM, especially the addition of HMPAM, the values of I1/I3 decreased but changed little with the increase of the concentration of DTAB, this means that pyrene is dissolved aside the polymer.(4)The phase boundaries of middle-phase microemulsion for the NaCl/H2O/l -heptane/ 1-pentanol systems in the absence of polymer, in the presence of unmodified poly(acrylamide) (PAM) and hydrophobically modified poly(acrylamide) (HMPAM) have been determined by varying salt concentration.The results showed that the polymer additive, especially HMPAM additive, promotes the formation of middle-phase microemulsion and induces a two- to three-phase transition at lower Cn8cl than that without HMPAM. This means the there is an intensity interaction between SDS and HMPAM, and the aggregates of HMPAM and SDS present the branched wormlike morphologies. Such structural aggregates may favor the formation of a sponge-like bicontinuous structure. Besides the widened range of the salt concentration in which the middle-phase microemulsion formed, HMPAM additives also reduce the volume of the middle-phase.(5) The interfacial tensions of the middle-phase microemulsion with the excess oil phase and with the excess low aqueous phase were measured. The results show that all the interfacial tensions become ultralow. In the microemulsion with HMPAM, it exhibits the higher interfacial tensions than those with PAM and without polymer. This is mainly because that after adding HMPAM, its longer alkyl chain leads to the strong hydrophobic interaction between polymer side chain and the alkyl chain of the pentanol. The hydrophobic interaction leads that a part of pentanol molecules associate with HMPAM, thus some of the pentanol molecules in the interfacial membrane were brought into the bulk solution (Alcohol can decrease the repulsion between the ion beams of the ionic surfactant and contributes to form a compact blend adsorptive layer, which can decrease interfacial tension efficiently).(6)The micro-environments of the system without polymer, with PAM/ HMPAM have been measured. The results show that all the I1/I3 values are...