posted on 2017-09-07, 17:59authored byKyle J. Johnson, Emmanouil Glynos, Serafeim-Dionysios Maroulas, Suresh Narayanan, Georgios Sakellariou, Peter F. Green
Incorporating nanoparticles
(NPs) within a polymer host to create
polymer nanocomposites (PNCs) while having the effect of increasing
the functionality (e.g., sensing, energy conversion) of these materials
influences other properties. One challenge is to understand the effects
of nanoparticles on the viscosity of nanoscale thick polymer films.
A new mechanism that contributes to an enhancement of the viscosity
of nanoscale thick polymer/nanoparticle films is identified. We show
that while the viscosities of neat homopolymer poly(2-vinylpyridine)
(P2VP) films as thin as 50 nm remained the same as the bulk, polymer/nanoparticle
films containing P2VP brush-coated gold NPs, spaced 50 nm apart, exhibited
unprecedented increases in viscosities of over an order of magnitude.
For thicker films or more widely separated NPs, the chain dynamics
and viscosities were comparable to the bulk values. These resultsNP
proximities and suppression of their dynamicssuggest a new
mechanism by which the viscosities of polymeric liquids could be controlled
for nanoscale applications.