Nanoscale physics
Structure analysis of anionic surfactant – poly (ethylene glycol) micellar aggregates by neutron scattering 
Artykulnyi O.P.1,2, Petrenko V.I.1,2, Avdeev M.V. 2, Ivankov O.I.2, 
Bulavin L.A. 1
1Faculty of Physics of Taras Shevchenko National University of Kyiv. Hlushkova Avenue, 4, Kyiv-03127, Ukraine. 
E-mail: artykulnyi@gmail.com
2 Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie str. 6, Dubna-141980, Russia.

Micellar systems of anionic surfactants sodium oleate (SO) and dodecylbenzene sulphonic acid (DBSA) are widely used for double layer sterically stabilization of magnetic nanoparticles in aqueous ferrofluids. The physicochemical properties of micellar buffer directly influence on the ferrofluids structural organization should be considered in the synthesis protocol [1].
Water-soluble neutral polymer poly (ethylene glycol) (PEG) is actively used in aqueous ferrofluids to increase its biocompatibility [2]. Also, it was shown the properties of the final ferrofluid depend on PEG molecular mass and concentration.
In present work, we study structural and interaction parameters of SO and DBSA micellar systems under the effect of the addition of PEG. Small-angle neutron scattering (SANS) together with the surface tension study allowed us to determine the micelle parameters of aggregation number, degree of ionization, the axial ratio of micelle shape and inverse screening length for various compositions of the mixed solutions [2,3]. It was shown that different ratio of substance concentration and polymer molecular mass leads to quantitative and qualitative changes of studied parameters due to a complex, multi-step process of polymer-surfactant interaction.

1.	 Petrenko, V. I.; Artykulnyi, O. P.; Bulavin, L. A.; et al. On the impact of surfactant type on the structure of aqueous ferrofluids // Colloid Surface A.- 2018.- 541.-P 222-226.
2.	 Illés, E., Szekeres, M., Kupcsik, E., et al. PEGylation of surfacted magnetite core–shell nanoparticles for biomedical application // Colloid  Surface A.- 2014.- 460.-P. 429-440.
3.	 Artykulnyi, O. P., Petrenko, V. I., Bulavin, L. A., et al. Impact of poly (ethylene glycol) on the structure and interaction parameters of aqueous micellar solutions of anionic surfactants // J. Mol. Liq.- 2019.- 276.-P 806-811.