Molecular simulation of hybrid polymer nanocomposites with organic nanodimers and inorganic nanorods: from structure and dynamics to viscosity Escañuela Copado, Adrián David Martín Molina, Alberto Patti, Alessandro polymer nanocomposites Molecular Dynamics nanoparticles viscosity A. E.-C. and A. P. acknowledge financial support from the U. S. Army Research Office under grant agreement 80692-SM-INT. A. P. is supported by a “Maria Zambrano Senior” researcher fellowship, financed by the European Union within the NextGenerationEU program and the Spanish Ministry of Universities. A.P. and A. M.-M. acknowledge, respectively, grants PID2022-136540NB-I00 and PID2023-149387OB-100 awarded by MICIU/AEI/10.13039/501100011033 and ERDF A way of making Europe. A.P. also acknowledges grant P21_00015 funded by Junta de Andalucıa - Consejerıa de Universidad, Investigación e Innovación. A. M.M thanks ERDF Andalusia Program 2021-2027 (Grant C-EXP-187-UGR23) for providing financial support. A. E.-C. thanks Iván M. Zerón for useful and fruitful discussions on the intricacies of the Green-Kubo calculations on viscosity. All authors thank Servicio de Supercomputación UGR and PROTEUS, the supercomputing center of Institute Carlos I for Theoretical and Computational Physics, for computational time provided. Polymer nanocomposites (PNCs) are cutting-edge materials that enhance polymer matrices with nanoparticles to achieve superior performance. The properties of these composites are significantly influenced by interactions at the nanoparticle-polymer interface. This study explores how inorganic nanorods (NRs) and various organic nanodimers (NDs)—differentiated by their interaction with the polymer and including Janus types—impact the structural, dynamical, and viscosity of PNCs. Through molecular simulations, we reveal how these nanoparticles interact within block copolymer and homopolymer matrices. Our findings show that ND-monomer interactions notably affect ND organization and improve barrier properties, while the structuring of NRs contributes to increased mechanical resistance. Furthermore, different PNCs provide a wide range of thickening behavior depending on the polymer matrix and the embedded nanoparticles. We observe increments of up to six times the melt’s viscosity when both nanoparticles are introduced in copolymers. The viscosity of the systems is evaluated using a non-equilibrium method, the SLLOD algorithm, and the Green- Kubo relation to obtain both the shear-thinning curve and the zero-shear viscosity value. These results underscore the importance of nanoparticle interactions and configurations in determining PNC behavior, providing critical insights for advancing material design and functionality. 2025-04-28T10:26:02Z 2025-04-28T10:26:02Z 2025 journal article Published version: A. Escañuela Copado, A. Martín Molina, A. Patti, Molecular Simulation of hybrid polymer nanocomposites with organ ic nanodimers and inorganic nanorods: from structure and dynamics to viscosity, The Journal of Chemical Physics, in press, 2025 https://hdl.handle.net/10481/103834 eng http://creativecommons.org/licenses/by-nc-nd/3.0/ open access Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License AIP