title: Big Effect of Small Nanoparticles: A Shift in Paradigm for Polymer Nanocomposites.
abstract: Polymer nanocomposites (PNCs) are important materials that are widely used in many current technologies and potentially have broader applications in the future due to their excellent property tunability, light weight, and low cost. However, expanding the limits in property enhancement remains a fundamental scientific challenge. Here, we demonstrate that well-dispersed, small (diameter ∼1.8 nm) nanoparticles with attractive interactions lead to unexpectedly large and qualitatively different changes in PNC structural dynamics in comparison to conventional nanocomposites based on particles of diameters ∼10-50 nm. At the same time, the zero-shear viscosity at high temperatures remains comparable to that of the neat polymer, thereby retaining good processability and resolving a major challenge in PNC applications. Our results suggest that the nanoparticle mobility and relatively short lifetimes of nanoparticle-polymer associations open qualitatively different horizons in the tunability of macroscopic properties in nanocomposites with a high potential for the development of advanced functional materials.
authors.forename: Shiwang
authors.identifier: 0000-0001-7396-4407
authors.initials: S
authors.lastname: Cheng
authors.affiliation: Departments of Materials Science and Chemistry, Frederick Seitz Materials Research Laboratory, University of Illinois , Urbana, Illinois 61801, United States.
authors.forename: Shi-Jie
authors.identifier: 0000-0003-3317-4720
authors.initials: SJ
authors.lastname: Xie
authors.forename: Jan-Michael Y
authors.identifier: 0000-0001-8774-697X
authors.initials: JY
authors.lastname: Carrillo
authors.forename: Bobby
authors.initials: B
authors.lastname: Carroll
authors.forename: Halie
authors.initials: H
authors.lastname: Martin
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Cao
authors.forename: Mark D
authors.identifier: 0000-0003-4304-6087
authors.initials: MD
authors.lastname: Dadmun
authors.forename: Bobby G
authors.initials: BG
authors.lastname: Sumpter
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Novikov
authors.affiliation: Departments of Materials Science and Chemistry, Frederick Seitz Materials Research Laboratory, University of Illinois , Urbana, Illinois 61801, United States.
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Schweizer
authors.forename: Alexei P
authors.initials: AP
authors.lastname: Sokolov
keywords: apparent disentanglement; fragility; glass transition; polymer nanocomposites; small nanoparticles