Campus Units

Chemical and Biological Engineering, Materials Science and Engineering, Neuroscience, Ames Laboratory, Physics and Astronomy

Document Type

Article

Research Focus Area

Advanced and Nanostructured Materials

Publication Version

Accepted Manuscript

Publication Date

3-2021

Journal or Book Title

Journal of Colloid and Interface Science

Volume

585

First Page

312

Last Page

319

DOI

10.1016/j.jcis.2020.11.080

Abstract

Hypothesis

Grafting nanoparticles surfaces with water-soluble polymers modify interparticle interactions that are pivotal for assembling them into ordered phases. By manipulating salt concentrations of gold nanoparticles (AuNPs) that are grafted with poly(N-isopropylacrylamide) (PNIPAM-AuNPs), we hypothesize that various aggregated phases form at the suspension/vapor interface or in the bulk that depend on the molecular weight (MW) of PNIPAM and on salt concentrations.

Experiments

AuNPs are grafted with thiolated PNIPAM of molecular weights of 3 or 6 kDa, and grafting is confirmed by dynamic light scattering. Liquid-surfaces X-ray reflectivity and grazing incidence small-angle X-ray scattering are used to determine the density profiles of the suspension/vapor interface and their inplane structure as salt is added to the suspensions.

Findings

We find that surface enrichment is induced by adding NaCl to the suspensions, and that at low salt concentrations, the monoparticle layer formed is dispersed, and above a threshold salt concentration, depending on MW of PNIPAM, the PNIPAM-AuNPs order in a hexagonal structure. We show that the lattice constant of the two-dimensional hexagonal structure varies with salt concentration, and more significantly with MW of PNIPAM.

Comments

This is a manuscript of an article published as Minier, Samuel, Hyeong Jin Kim, Jonathan Zaugg, Surya K. Mallapragada, David Vaknin, and Wenjie Wang. "Poly (N-isopropylacrylamide)-grafted Gold Nanoparticles at the Vapor/Water Interface." Journal of Colloid and Interface Science 585 (2021): 312-319. DOI: 10.1016/j.jcis.2020.11.080. Posted with permission.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Copyright Owner

Elsevier Inc.

Language

en

File Format

application/pdf

Available for download on Sunday, November 27, 2022

Published Version

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