ISSN 0965-545X, Polymer Science, Ser. A, 2014, Vol. 56, No. 6, pp. 798–811. © Pleiades Publishing, Ltd., 2014. Original Russian Text © E.A. Karpukhina, S.O. Il’in, V.V. Makarova, I.B. Meshkov, V.G. Kulichikhin, 2014, published in Vysokomolekulyarnye Soedineniya. Ser. A, 2014, Vol. 56, No. 6, pp. 670–684. 798 INTRODUCTION Since the appearance of nanocomposites based on polymers, Nicolai Alfredovich Platé demon- strated sincere interest in this area. While observing the process of ordering of clay particles in a solution of polyisobutylene during flow, he said the key phrase “Well, this is the chaos–order transition!” This was the title of a paper that was published in 2009 and served as a basis for a series of studies awarded with the Grand Prize of the Nauka Pub- lishing House. It was Platé who emphasized the relationship between the physical chemistry of polymers and colloidal chemistry in the analysis of such objects. The study of rheological and relax- ation properties of macromolecular particles (den- drimers, MQ resins, silicasols) during the advance- ment of this direction at the Topchiev Institute of Petrochemical Synthesis (jointly with the Eniko- lopov Institute of Synthetic Polymer Materials) revealed that their behavior is similar to that of col- loid systems. It is natural that, at the next stage, mixtures of macromolecular particles with linear macromolecules were analyzed, because the organic shells of silicasols provided their compatibility with conventional polymers, while silica cores is essen- tially a nanosized filler. This analysis was performed with the use of two main methods: microinterfer- ometry, which makes it possible to estimate the mis- cibility of components at the optical level, and rhe- ology, which provides a way to ascertain difference in viscoelastic properties in various regions of the phase diagram. The synthesis and characterization of composite materials is an urgent line of modern science. These systems consist of two to several phases with different compositions and structures. Mixtures make it possi- ble to unite the properties of individual components to some extent and to attain synergistic behavior. Poly- mer nanocomposites—polymer matrixes containing solid nanoparticles distributed in them—belong to a new class of composite materials. Owing to high dis- persion of nanosized filler particles, these systems can feature unusual properties that cannot be achieved by conventional composites [1, 2]. This phenomenon is above all related to the high surface energy of nanopar- ticles and, as a consequence, to the high adsorption ability with respect to macromolecules of the polymer matrix that are close in polarity to nanoparticles. Therefore, macromolecules in the adsorption layers acquire unnatural, frequently extended conforma- tions; as a result, reinforcement of the polymer occurs even at filler concentrations below the percolation threshold. Components with similar polarities pre- serve a certain similarity of the chemical structures of interfaces between particles and the adsorption layer of macromolecules of the matrix polymer. Phase State and Rheology of Polyisobutylene Mixtures with Decyl Surface Modified Silica Nanoparticles E. A. Karpukhina a , S. O. Il’in a *, V. V. Makarova a , I. B. Meshkov b , and V. G. Kulichikhin a a Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Leninskii pr. 29, Moscow, 119991 Russia b Enikolopov Institute of Synthetic Polymer Materials, Russian Academy of Sciences, Profsoyuznaya ul. 70, Moscow, 117393 Russia *e-mail: s.o.ilyin@gmail.com Received April 16, 2014; Revised Manuscript Received June 9, 2014 Abstract—The miscibility of linear polyisobutylene and silica nanoparticles with surfaces modified by decyl groups is studied. The phase state of these systems corresponds to the amorphous equilibrium and may be described by a binodal with the UCST. As the radius of the inorganic core of nanoparticles and the molecular mass of polyisobutylene increase, the insolubility region on the phase diagram becomes wider. The addition of nanoparticles to the polymer leads to decreases in the viscoelastic characteristics of homogeneous media and provides the non-Newtonian behavior of the composition in the two-phase region. Shear deformation causes shifts of the phase equilibrium lines in the direction depended on the sizes of the nanoparticles. DOI: 10.1134/S0965545X14060066 80th ANNIVERSARY OF N.A. PLATÉ