Localized and Collective Dynamics in Liquid-like Polyethylenimine-Based Nanoparticle Organic Hybrid Materials

• DOI: 10.1021/acs.macromol.0c02370
• Publication Date: 2021-02-18T00:06:14Z
• Authors: Emmanuel Urandu M...; Nelly M. Cantillo; Sara T. Hamilton; Matthew A. Harris; Thomas A. Zawodzi...; Ah-Hyung Alissa Park; Joshua Sangoro
• Keywords: Polyethylenimine; Mesoscopic physics

Broadband dielectric spectroscopy, rheology, and nuclear magnetic resonance spectroscopy are employed to study molecular dynamics in a nanoparticle organic hybrid material (NOHMs) system comprising 20 wt % silica nanoparticles ionically bonded polyethylenimine canopy. By comparing the neat polymer (used as canopy) derivative NOHMs, we find that timescales characterizing segmental NOHM identical those for polymer. Detailed analysis of carbon-spin lattice relaxation times yields mechanistic insights into localized collective dynamics, quantitative agreement with results. Interestingly, NOHMs retain liquid-like characteristics unlike conventional nanocomposites but exhibit higher viscosity due additional contributions from tethered chains mesoscopic structuring. These findings demonstrate potential achieving unique desired properties via by an informed choice canopy material.