Résumé
Small-angle neutron scattering is the perfect tool to study the average conformation of macromolecules in about any environment, from solvents to other polymer molecules. The power of the method is intimately related to the length scale of observation, the virtual absence of artefacts due to the averaging, and most importantly, the possibilities to adjust contrasts and highlight chosen parts of the samples. In this talk, some recent applications will be reviewed. During a stay with Arantxa Arbe and Juan Colmenero (San Sebastian), we have studied the structure of synthetic single-chain nanoparticles (SCNPs) in presence of linear polystyrene crowding molecules under contrast-matching of the crowders [1]. A model describing the scattering of aggregating polydisperse SCNPs has been developed, resulting in the determination of the potentially squeezed size of the individual SCNPs within aggregates, their local chain statistics, and the average aggregation number, as a function of crowding. Secondly, in collaboration with Marian Cors and Thomas Hellweg (Bielefeld), we have investigated the internal structure of core-shell microgel particles in suspension. Using selective deuteration, core- and shell monomers could be measured independently, and the corresponding monomer profile described by a reverse Monte Carlo approach [2]. In the last part, an application to polymer nanocomposites will be discussed. Rubber-based nanocomposites show a large variety of spatial organization of the filler nanoparticles, which can be studied by small-angle scattering, and analyzed by large-scale reverse Monte Carole simulation [3]. A key feature of rubber nanocomposites is linked to the influence of the filler surfaces on the polymer structure and dynamics, [4]. In particular, we have studied blends of short and long chains, where one chain type is deuterated, by small-angle neutron scattering. Different degrees of spatial segregation could be identified, including a peculiar, “fish-shaped” interfacial gradient. [1] J. Oberdisse, M. González-Burgos, A. Mendia, A. Arbe, A. J. Moreno, J. A. Pomposo, A. Radulescu and J. Colmenero, Macromolecules, 2019, 4295.[2] M. Cors, O. Wrede, L. Wiehemeier, A. Feoktystov, F. Cousin, T. Hellweg, J. Oberdisse, Scientific Reports 2019, 9, 13812.[3] D. Musino, A.-C. Genix, T. Bizien, J. Oberdisse, Nanoscale, 2020, 12, 3907.[4] A.C. Genix, V. Bocharova, B. Carroll, P. Dieudonné-George, M. Sztucki, R. Schweins, A. P. Sokolov, and J. Oberdisse, ACS Applied Materials and Interfaces 2021, 13, 36262.