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Effect of a Hydrophilic PEO–PPO–PEO Copolymer on Cetyltrimethyl Ammonium Tosylate Solutions in Water
Author(s) -
Patel Vijay,
Chavda Suresh,
Aswal Vinod K.,
Bahadur Pratap
Publication year - 2012
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-011-1309-9
Subject(s) - micelle , copolymer , chemistry , viscoelasticity , chemical engineering , polymer chemistry , conductance , organic chemistry , composite material , aqueous solution , materials science , polymer , combinatorics , engineering , mathematics
Cetyltrimethyl ammonium tosylate (CTAT) in water forms long flexible wormlike micelles at concentrations above 10 mM, leading to highly viscous solutions and viscoelastic stiff gels above 100 mM. In the presence of a nonmicellar hydrophilic PEO–PPO–PEO triblock copolymer F87 (TBC‐F87, Total mol.wt. = 7,700, EO = 70%) these wormlike micelles RE transformed into smaller structures, as evident from a sharp decrease in viscosity and increase in specific conductance. These results are quantified by small angle neutron scattering (SANS) measurements. The PPO middle block of TBC‐F87 gets inserted in the CTAT micelle, the size and total aggregation number of CTAT/TBC‐F87 mixed micelles decreased but the number of TBC‐F87 molecules in the mixed micelles increased with an increase in [TBC‐F87]. Two break points in the typical specific conductance versus CTAT concentration plot at various [TBC‐F87] amounts represent interactions between CTAT and TBC‐F87. The penetration of PPO of TBC‐F87 inside CTAT micelles decreases hydrophobicity of the core while the presence of PEO end blocks enhances hydrophilicity each favoring smaller micelles.