Nanoparticle Structure and Dynamics in Polymer Nanocomposites

The physical properties of polymers can be significantly altered both by embedding nanoparticles within them and by grafting them to nanoparticle surfaces. The ability to predict and measure the structure, dynamics, and thermodynamics of grafted polymers is central to purposefully creating new nanocomposite materials. In particular, one powerful technique for studying these aspects of nanocomposites is neutron scattering. This talk will review recent work we have performed to study the behavior of nanoparticles in nanocomposite materials, with a focus on nanorods and nanospheres. Small-angle neutron scattering measurements of poly(ethylene oxide)-grafted Au nanorods, poly(methyl acrylate)-grafted SiO₂ nanospheres, and poly(methyl methacrylate)-grafted Fe₃O₄ nanosheres will be discussed, along with approaches to interpret the scattering results. The conformation of the grafted polymers will be compared between solution and nanocomposite states. Neutron spin echo measurements of the relaxation dynamics of grafted chain will be discussed, and the trends compared to the results of recent dissipative particle dynamics (DPD) calculations done by us.