A multi-Lorentzian-splitting algorithm is used to distinguish the 1H NMR signal of free PEG from that of grafted PEG, therefore allowing monitoring of the grafting process in situ.

Adding small nanoparticles (NPs) into polymer melt can lead to a non-Einstein-like decrease in viscosity. However, the underlying mechanism remains a long-standing unsolved puzzle. Here, for an all-polymer nanocomposite formed by linear polystyrene (PS) chains and PS single-chain nanoparticles (SCNPs), we perform large-scale molecular dynamics simulations and experimental rheology measurements. We show that with a fixed (small) loading of the SCNP, viscosity reduction (VR) effect can be largely amplified with an increase in matrix chain length , and that the system with longer polymer chains will have a larger VR. We demonstrate that such -dependent VR can be attributed to the friction reduction experienced by polymer segment blobs which have similar size and interact directly with these SCNPs. A theoretical model is proposed based on the tube model. We demonstrate that it can well describe the friction reduction experienced by melt polymers and the VR effect in these composite systems.

The mechanical properties of polymer nanocomposites containing bimodal grafted nanoparticles can be tuned at the nanoparticle/polymer interface using different graft chain types.