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.

Structure and properties of nanocomposites based on PTT-block-PTMO copolymer and graphene oxide prepared by in situ polymerization

“…Whereas at higher GO loading, the polymer-GO and GO-GO interactions are predominate and causes increase the melt bulk viscosity. The possible mechanisms of selective adsorption [37], excluded free volume [38] and ball-bearing effect [39] are also reported in literature to explain the decrease in melt viscosity when nanofillers are introduced to the polymer matrix. Another possible explanation for observed melt viscosity changes with GO loading can result from lubricant behaviour of graphite [40].…”

A review on the role of interface in mechanical, thermal, and electrical properties of polymer composites

“…For different polymer nanocomposites, T g was shown to be increased [206,207], decreased [180,208], or even unaffected [182,209] by the introduction of fillers into the system. More studies are summarized in Table 2.…”

Graphitic nanofillers in PMMA nanocomposites—An investigation of particle size and dispersion and their influence on nanocomposite properties

“…9,51,52 For the GNP/ PMMA composite, the GNP particles were dispersed in tetrahydrofuran (THF) via bath sonication (Branson 3510, 335W setting, Branson Instrument, Danbury, CT) for 30 min. An appropriate amount of PMMA was dissolved in a minimum amount of THF ($30 mL) in another vial and combined with the dispersed suspension of GNP in THF.…”