Interaction between cationic, anionic and non-ionic surfactants with ABA block copolymer Pluronic PE6200 and with BAB reverse block copolymer Pluronic 25R4

The interaction in aq. soln. between either the normal block copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide): Pluronic PE6200 [(EO)11(PO)28(EO)11], or the reverse block copolymer poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide): Pluronic 25R4 [(PO)19(EO)33(PO)19] and the surfactants Na decylsulfate, C10OS, decyltrimethyl NH4Br, C10TAB, and pentaethylene glycol monodecyl ether, C10E5, was studied and the aggregation behavior of these surfactants with Pluronics was compared. Surface tension measurements show that Pluronics in their nonaggregated state better interact with the anionic surfactant C10OS than with cationic and nonionic ones. The presence of the 2 Pluronics induces the same lowering of the aggregation no. of C10OS as shown by fluorescence quenching measurements. The no. of polymer chains necessary to bind each C10OS aggregate is .apprx.6 for PE6200 and .apprx.2 for 25R4. Also, this surfactant also induces the same increment in the gyration radius of the polymers as revealed by viscosimetry. Calorimetric results were reasonably reproduced by applying a simple equil. model to the aggregation processes.