35 ISSN 1811-2382, Polymer Science, Series C, 2017, Vol. 59, No. 1, pp. 35–48. © Pleiades Publishing, Ltd., 2017. Original Russian Text © E.A. Lysenko, R.S. Bilan, P.S. Chelushkin, 2017, published in Vysokomolekulyarnye Soedineniya, Seriya C, 2017, Vol. 59, No. 1, pp. 40–54. Block-Copolymer Micelles with a Interpolyelectrolyte Crown E. A. Lysenko а, *, R. S. Bilan b , and P. S. Chelushkin с а Faculty of Chemistry, Moscow State University, Moscow, 119991 Russia b Moscow Institute of Engineering Physics, Kashirskoe sh. 31, Moscow, 115409 Russia с Institute of Macromolecular Compounds, Russian Academy of Sciences, Bol’shoi pr. 31, St. Petersburg, 199004 Russia *е-mail: ealysenko@rambler.ru Received September 19, 2016 Abstract—The dispersion stability, structure, and properties of polymer micelles with the hydrophobic core and the interpolyelectrolyte crown in dilute water–salt solutions are studied by turbidimetry, velocity sedimentation, static and dynamic light scattering, fluorescence spectroscopy, and electron microscopy, as well as by measuring the electrophoretic mobility of the particles. The micelles are obtained by mixing diblock copolymers PS–block- poly(N-ethyl-4-vinylpyridine bromide) and PS–block-poly(acrylic acid) by a specially developed technique of water introduction in the mixture of copolymers in a nonselective organic solvent. It is found that the dispersion stability and the structural and physicochemical characteristics of micelles with the interpolyelectrolyte crown depend on the balance of electrostatic interactions of similarly and oppositely charged units in the crown. In turn, this balance is determined by the composition of the interpolyelectrolyte crown as well as by the pH and ionic strength of solution. It is shown that the micelles with the interpolyelectrolyte crown can be considered to be a spe- cial type of polyelectrolyte nanoparticles combining the properties of polyelectrolyte micelles and interpolyelectro- lyte complexes. The unique ability of such micelles to electrostatically bind similarly charged polyions with a high linear charge density to the crown is demonstrated. It is first found that such a binding can be selective. DOI: 10.1134/S1811238217010076 INTRODUCTION As is known, the fundamental property of linear polyelectrolytes is their ability to interact with oppo- sitely charged macromolecules of different chemical nature to form a special class of macromolecular com- pounds—interpolyelectrolyte complexes (IPECs) [1– 3]. The incorporation of macromolecules into IPEC particles makes it possible to regulate their conforma- tional state, degree of aggregation, dispersion stability, and chemical and biological activity. A great interest in IPECs is related to their potential application as stabi- lizers and flocculants of colloid dispersions, binders, membranes, and nanoreactors and for the delivery of biologically active macromolecules into cells [4–6]. Polyelectrolyte micelles are the products of self- organization of ionogenic amphiphilic block copoly- mers in water–salt and water–organic media [7, 8]. The micelle structure consists of a hydrophobic core from the nonpolar blocks and a charged lyophilizing crown of polyelectrolyte blocks. The micelles are self- assembling nanoparticles with a high capacity and increased dispersion stability capable of solubilizing nonpolar compounds into the core and of binding oppositely charged particles into the crown [9]. In recent years, a number of studies have been devoted to the formation of IPECs between the micelles of iono- genic amphiphilic block copolymers and macromolecules of oppositely charged linear polyelectrolytes [10–14]. It was shown that the binding of oppositely charged polyions proceeds in the internal part of the micelle crown and leads to the formation of three-layered structures from the hydrophobic core, the interlayer of salt bonds from mutu- ally neutralized polyelectrolyte units (the IPEC layer), and the external lyophilizing shell (crown) from the excess polyelectrolyte units. Such complexes are called micellar IPECs. The amount of charges on macromolecules that can be bound to particles of micellar IPECs without loss in their dispersion stability is about 25–30% of the amount of charged units of initial micelles [10–12]. The progress in the investigation of micellar IPECs made it possible to set the issue pertaining to creation of universal polyelectrolyte micelles able to bind both posi- tively and negatively charged macromolecules of differ- ent chemical nature from aqueous solutions. The imple- mentation of the universality concept requires the pres- ence of cationic and anionic units in the polyelectrolyte micelle crown. Salt bonds may appear between the crown units; that is, intramicellar IPECs may form. The struc- ture, charge, and dispersion stability of the micelles will be determined by their composition, that is, the ratio of positively and negatively charged units in the crown, and the degree of ionization of these units. The binding of charged macromolecules by these micelles can be per- formed by both the interpolyelectrolyte compound reac- tions and the reactions of interpolyelectrolyte exchange and substitution. This creates prerequisites for manifesta- tion of selectivity by micelles during polyion binding.