Self-assembly in dilute mixtures of non-ionic and anionic surfactants and rhamnolipd biosurfactants.
The self-assembly of dilute aqueous solutions of a ternary surfactant mixture and rhamnolipid biosurfactant/surfactant mixtures has been studied by small angle neutron scattering. In the ternary surfactant mixture of octaethylene glycol monododecyl ether, C12E8, sodium dodecyl 6-benzene sulfonate, LAS, and sodium dioxyethylene monododecyl sulfate, SLES, small globular interacting micelles are observed over the entire composition and concentration range studied. The modelling of the scattering data strongly supports the assumption that the micelle compositions are close to the solution compositions. In the 5-component rhamnolipid/surfactant mixture of the mono-rhamnose, R1, di-rhamnose, R2, rhamnolipids with C12E8/LAS/SLES, globular micelles are observed over much of the concentration and composition range studied. However, for solutions relatively rich in rhamnolipid and LAS, lamellar/micellar coexistence is observed. The transition from globular to more planar structures arises from a synergistic packing in the 5 component mixture. It is not observed in the individual components nor in the ternary C12E8/LAS/SLES mixture at these relatively low concentrations. The results provide an insight into how synergistic packing effects can occur in the solution self-assembly of complex multi-component surfactant mixtures, and give rise to an unexpected evolution in the phase behaviour.
Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford, UK.
J R
JR
Liley
Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford, UK; ISIS, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, UK. Electronic address: jeff.penfold@stfc.ac.uk.
J
J
Penfold
Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford, UK.
R K
RK
Thomas
Unilever Research and Development Laboratory Port Sunlight, Quarry Road East, Bebington, Wirral, UK.
I M
IM
Tucker
Unilever Research and Development Laboratory Port Sunlight, Quarry Road East, Bebington, Wirral, UK.
J T
JT
Petkov
Unilever Research and Development Laboratory Port Sunlight, Quarry Road East, Bebington, Wirral, UK.
P S
PS
Stevenson
School of Bio-medical Sciences, University of Ulster, Coleraine, Northern Ireland, UK.
I M
IM
Banat
School of Bio-medical Sciences, University of Ulster, Coleraine, Northern Ireland, UK.
R
R
Marchant
School of Bio-medical Sciences, University of Ulster, Coleraine, Northern Ireland, UK.
M
M
Rudden
ISIS, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, UK.
A
A
Terry
Insitut-Laue Langevin, 71 Avenue des martyrs, CS 20156, 38042 Grenoble Cedex 09, France.
I
I
Grillo
D000476:Alkanesulfonates / Q000737:chemistry*; D001557:Benzenesulfonates / Q000737:chemistry; D006017:Glycolipids / Q000737:chemistry*; D008823:Micelles; D033363:Neutron Diffraction; D011092:Polyethylene Glycols / Q000737:chemistry; D012210:Rhamnose / Q000737:chemistry; D053838:Scattering, Small Angle; D012967:Sodium Dodecyl Sulfate / Q000031:analogs & derivatives / Q000737:chemistry; D012996:Solutions; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D000476:Alkanesulfonates; D001557:Benzenesulfonates; D006017:Glycolipids; D008823:Micelles; D012996:Solutions; D013501:Surface-Active Agents; C418382:rhamnolipid; D014867:Water; C017272:dodecyloctaethyleneglycol monoether; D012967:Sodium Dodecyl Sulfate; D011092:Polyethylene Glycols; C001114:dodecylbenzenesulfonic acid; C408148:sodium laureth sulfate; D012210:Rhamnose
Biosurfactants; Mixed micelles; Mixed surfactants; Self-assembly; Small angle neutron scattering