ИСТИНА

Glass transition in different systems and materials remains one of the most intriguing phenomena for both experimental and theoretical investigations in the area of condensed matter physics. A particularly interesting field of research in this respect is the investigation of glass transition of polymers [1]. Different polymers are applied in modern technologies and new fields of application are emerging. One of the most actively evolving research fields is connected with thin polymer films. Applications of thin films increase in technologies involving dielectric coatings, resist layers for lithography, electronic packaging, optical coatings, non-linear optical devices, lubricating surfaces, etc. Neutron scattering studies of polymers structure in glassy and liquid state have been performed during last 30 years and have proven to be very supportive [2]. The recently performed investigations of polymer thin films and glass transition of bulk polymer systems gave new insights. Presently, the most interesting topic is the study of polymer nanocomposites, and their glass transition, as new materials for technological applications [3]. The aim of the present report is to give the insight on recent research on polymer thin films glass transition, including the latest experiments performed by us at the GRAINS instrument of the IBR-2 reactor. The initial investigations of polystyrene (PS) and PS thin films glass transition via neutron reflectometry (NR) were performed in 2015. The first results have shown that the conducted and planned experiments are achievable from methodological part. The late experiment was aimed at obtaining the new scientific results for the glass transition in polymer thin films and polymer/carbon nanoparticles mixtures films. At the GRAINS instrument (reflectometry from liquid-containing interfaces) the specular reflectivity was measured and analyzed for free surface of d-PS/C60 samples in the temperature range covering the transitional region between molten and amorphous glassy states (40-135 ºC). The analysis allowed analyzing the influence of nanoparticles on glass transition temperature of thin films, as well as speculating about the internal structure of these thin films, a highly debated subject in the literature at present. [1] T.V. Tropin, J.W.P. Schmelzer, V.L. Aksenov (2016). Modern Aspects of the kinetic theory of glass transition. Physics – Uspekhi. 59(1), 42-66. [2] R. Inoue, et. al (2011). Interfacial properties of polystyrene thin films as revealed by neutron reflectivity. Physical Review E. 84, 031802. [3] D. Cangialosi, et. al (2013). Physical aging in polymers and polymer nanocomposites: recent results and open questions”. Soft Matter. 9(36), 8619.