Microscopic Structure and Dynamics of Attractive Polymer Nanocomposites

Polymer nanocomposites (PNC) enhance the mechanical, optical, and electrical properties relative to the host polymer and are already widely applied and studied because of their potentials in tunability, responsiveness, and functionality. However, sufficient understanding of the structure-dynamics-property relationship of these materials are lacking. Here, silica nanoparticles (SiO₂) in various shapes and sizes are investigated as model attractive PNC using scattering methods and rheology to connect the molecular level structure and dynamics to the macroscopic property. Small angle scattering techniques provide information on the dispersion of the nanoparticles as well as the conformation of the polymer chains. Dynamic neutron scattering techniques, such as backscattering and spin echo, are used to measure the effect of the different nanoparticles on the Rouse dynamics and entanglement density. Data are interpreted in terms of standard theories developed for bulk polymers providing a mean to connect the microscopic dynamics to the observed rheological behavior. The results provide insights into the role of surface, volume and nanoparticle dispersion in polymer matrix and shed light on how polymer dynamics is related to mechanical reinforcement of PNC.