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Concentration boundaries within which polymer-colloid structures exist in a sodium dodecyl sulfate-polyethyleneimine-water system were determined. The catalytic effect of this composition was found for the hydrolysis of phosphonic acid esters. The found accelera tion of hydrolysis up to 25 fold is caused by reagent concentrating in a catalytic complex.Mixed systems surfactant-polymer are objects of a promising interdisciplinary scientific area that attract great researchers´ interest. 1-6 The development of this avenue of investigation is stimulated by a wide scope of practi cally useful properties of mixed solutions and a possibility of their purposeful control by the variation of the compo nent ratio in the system. In addition, the study of regulari ties of the formation of polymolecular ensembles extends potentialities of self assembly modelling in biological sys tems. The main goal of fundamental studies of aqueous surfactant-polymer solutions is to prove the combined aggregation, find concentration boundaries for the exist ence of mixed structures, estimate their stability, and char acterize the nature of intermolecular interactions. The reactivity of compounds in mixed polymer-colloid sys tems is poorly studied and, therefore, is one of the main tasks of the present work.We have previously 7,8 studied the physical and cata lytic properties of polymer-colloid systems based on the cationic surfactant cetyltrimethylammonium bromide (CTAB) and polyethyleneimine (PEI). Different points of view about the possible cooperative binding of cationic surfactants with nonionic and likely charged polymers can be found in the literature. 9 The published results 7,8 favor the hypothesis on the self organization and forma tion of supramolecular structures in the CTAB-PEI sys tem. These structures efficiently catalyze the hydrolysis of phosphorus esters. Taking into account that the electro static interaction contributes unfavorably to the free en ergy of formation of complexes of the likely charged sur factant and polymeric species, it should be assumed that combined aggregates are formed in these systems mainly due to hydrophobic interactions. To gain more compre hensive information on the contribution from differ ent types of intermolecular interactions in the surfac tant-polymer systems, we continued to study the cata lytic properties of PEI based compositions, using an un likely charged surfactant, sodium dodecyl sulfate (SDS). The hydrolysis of phosphonates 1-3 was studied as a model process (Scheme 1). Scheme 1 1 2 3 X NO 2 NO 2 Br R Et n С 6 Н 13 Et ExperimentalCompounds 1-3 were synthesized by a known procedure. 10 Sodium dodecyl sulfate (Sigma) and branched PEI (Aldrich, molecular weight 30000) containing the primary, secondary, and tertiary nitrogen atoms in a ratio of 1 : 2 : 1 were used. Molar concentrations of PEI presented in the work are based on the

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