Title
Poly(N-isopropylacrylamide)-grafted gold nanoparticles at the vapor/water interface
Publication Date
11-27-2020
Department
Chemical and Biological Engineering; Materials Science and Engineering; Neuroscience; Ames Laboratory; Physics and Astronomy
Campus Units
Ames Laboratory, Chemical and Biological Engineering, Materials Science and Engineering, Physics and Astronomy, Neuroscience
OSTI ID+
1735334
Report Number
IS-J 10367
DOI
10.1016/j.jcis.2020.11.080
Journal Title
Journal of Colloid and Interface Science
Volume Number
585
First Page
312
Last Page
319
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.
DOE Contract Number(s)
AC02-07CH11358
Language
en
Publisher
Iowa State University Digital Repository, Ames IA (United States)
