The performance of polymer nanocomposites depends on polymer-nanoparticle compatibility and dispersion quality, as interfacial dynamics often deviate from bulk properties. We prepare loop-grafts on silica nanoparticles and characterize the success of loop formation in these complex hybrid systems. In this talk, I will present the synthesis of poly(methyl methacrylate) (PMMA) loop-grafted nanoparticles and how loop constrains influence the glass-transition temperature ( ) compared to that of linear-grafted ones. Next, I will discuss the all-PMMA composite results, where PMMA grafted particles are dispersed in PMMA matrix. For the composites, PMMA matrix were selected below and above the entanglement molecular weight of PMMA, and the composites were prepared at 5 wt% silica core loading. Differential scanning calorimetry showed a pronounced increase the of the loop composites compared to the linear. Complementary dielectric relaxation measurement showed a slowdown in the mean relaxation time in the loop composites, suggesting more restricted chain mobility. These are evident of a complex heterogeneous interphase posed by the loop particle which could inspire new strategies to design network forming interphases with tunable mechanical properties.
