Suspensions of polymer-grafted nanoparticles with added polymers—Structure and effective pair-interactions

Chandran, Sivasurender ; Saw, Shibu ; Kandar, A. K. ; Dasgupta, C. ; Sprung, M. ; Basu, J. K. (2015) Suspensions of polymer-grafted nanoparticles with added polymers—Structure and effective pair-interactions The Journal of Chemical Physics, 143 (8). 084902. ISSN 0021-9606

Full text not available from this repository.

Official URL: http://doi.org/10.1063/1.4929438

Related URL: http://dx.doi.org/10.1063/1.4929438

Abstract

We present the results of combined experimental and theoretical (molecular dynamics simulations and integral equation theory) studies of the structure and effective interactions of suspensions of polymer grafted nanoparticles (PGNPs) in the presence of linear polymers. Due to the absence of systematic experimental and theoretical studies of PGNPs, it is widely believed that the structure and effective interactions in such binary mixtures would be very similar to those of an analogous soft colloidal material-star polymers. In our study, polystyrene-grafted gold nanoparticles with functionality f = 70 were mixed with linear polystyrene (PS) of two different molecular weights for obtaining two PGNP:PS size ratios, ξ = 0.14 and 2.76 (where, ξ = Mg/Mm, Mg and Mm being the molecular weights of grafting and matrix polymers, respectively). The experimental structure factor of PGNPs could be modeled with an effective potential (Model-X), which has been found to be widely applicable for star polymers. Similarly, the structure factor of the blends with ξ = 0.14 could be modeled reasonably well, while the structure of blends with ξ = 2.76 could not be captured, especially for high density of added polymers. A model (Model-Y) for effective interactions between PGNPs in a melt of matrix polymers also failed to provide good agreement with the experimental data for samples with ξ = 2.76 and high density of added polymers. We tentatively attribute this anomaly in modeling the structure factor of blends with ξ = 2.76 to the questionable assumption of Model-X in describing the added polymers as star polymers with functionality 2, which gets manifested in both polymer-polymer and polymer-PGNP interactions especially at higher fractions of added polymers. The failure of Model-Y may be due to the neglect of possible many-body interactions among PGNPs mediated by matrix polymers when the fraction of added polymers is high. These observations point to the need for a new framework to understand not only the structural behavior of PGNPs but also possibly their dynamics and thermo-mechanical properties as well.

Item Type:Article
Source:Copyright of this article belongs to FOIA Privacy.
ID Code:116077
Deposited On:22 Mar 2021 07:01
Last Modified:22 Mar 2021 07:01

Repository Staff Only: item control page