title: Effect of hydrophobically modified polymer on salt-induced structural transition in microemulsions.
abstract: The phase boundaries of the middle-phase microemulsion for NaCl/SDS/H2O/1-heptane/1-pentanol systems in the absence of polymer and in the presence of unmodified poly(acrylamide) (PAM) and hydrophobically modified poly(acrylamide) (HMPAM) have been determined at varying salt concentrations. These three middle-phase microemulsions (with HMPAM, with PAM, and without polymer) were studied using interfacial tension measurement, steady-state fluorescence, and time-resolved fluorescence quenching. Compared to the polymer-free system and the system with PAM, the addition of HMPAM significantly enlarges the range of the salt concentrations for the formation of the middle-phase microemulison and causes both the excess oil and aqueous phases to increase in volume at the expense of the middle-phase microemulsion. For the middle-phase microemulsion with HMPAM, the interfacial tensions of the microemulsion phase with the excess oil phase and with the excess aqueous phase are all ultralow and exhibit higher values than those with PAM and without polymer. At the same salt concentration, the apparent surfactant aggregation number in the middle-phase microemulsion with HMPAM has the smallest value among these three systems. All results indicate that the strong interaction of surfactant with hydrophobically modified polymer has a large effect on the formation and properties of the middle-phase microemulsion.
authors.affiliation: Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, PR China.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Ma
authors.forename: Xiaoyong
authors.initials: X
authors.lastname: Wang
authors.forename: Jinben
authors.initials: J
authors.lastname: Wang
authors.forename: Donghong
authors.initials: D
authors.lastname: Guo
authors.forename: Yilin
authors.initials: Y
authors.lastname: Wang
authors.forename: Jianping
authors.initials: J
authors.lastname: Ye
authors.forename: Zhengping
authors.initials: Z
authors.lastname: Wang
authors.forename: Haike
authors.initials: H
authors.lastname: Yan
mesh_terms: D020106:Acrylamide / Q000737:chemistry*; D004655:Emulsions; D006536:Heptanes / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D000439:Pentanols / Q000737:chemistry; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D004655:Emulsions; D006536:Heptanes; D000439:Pentanols; D011108:Polymers; D014867:Water; D020106:Acrylamide; D012967:Sodium Dodecyl Sulfate; D012965:Sodium Chloride; C028618:n-heptane; C024999:n-pentanol