title: Nanoscale effects leading to non-Einstein-like decrease in viscosity.
abstract: Nanoparticles have been shown to influence mechanical properties; however, transport properties such as viscosity have not been adequately studied. This might be due to the common observation that particle addition to liquids produces an increase in viscosity, even in polymeric liquids, as predicted by Einstein nearly a century ago. But confinement and surface effects provided by nanoparticles have been shown to produce conformational changes to polymer molecules, so it is expected that nanoparticles will affect the macroscopic viscosity. To minimize extraneous enthalpic or other effects, we blended organic nanoparticles, synthesized by intramolecular crosslinking of single polystyrene chains, with linear polystyrene macromolecules. Remarkably, the blend viscosity was found to decrease and scale with the change in free volume introduced by the nanoparticles and not with the decrease in entanglement. Indeed, the entanglements did not seem to be affected at all, suggesting unusual polymer dynamics.
authors.affiliation: Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA. mackay@msu.edu
authors.forename: Michael E
authors.initials: ME
authors.lastname: Mackay
authors.forename: Tien T
authors.initials: TT
authors.lastname: Dao
authors.forename: Anish
authors.initials: A
authors.lastname: Tuteja
authors.forename: Derek L
authors.initials: DL
authors.lastname: Ho
authors.forename: Brooke
authors.initials: B
authors.lastname: van Horn
authors.forename: Ho-Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Hawker
mesh_terms: D004058:Diffusion; D046911:Macromolecular Substances; D008863:Microspheres; D008968:Molecular Conformation; D009038:Motion; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry* / Q000145:classification*; D012212:Rheology / Q000379:methods*; D012996:Solutions / Q000737:chemistry*; D013696:Temperature; D014783:Viscosity
chemical_list: D046911:Macromolecular Substances; D011137:Polystyrenes; D012996:Solutions