Poly(N-isopropylacrylamide)-grafted gold nanoparticles at the vapor/water interface
- Ames Lab., Ames, IA (United States)
- Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
- Iowa State Univ., Ames, IA (United States)
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 observe 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.
- Research Organization:
- Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; USDOE
- Grant/Contract Number:
- AC02-07CH11358
- OSTI ID:
- 1735334
- Alternate ID(s):
- OSTI ID: 1775885
- Report Number(s):
- IS-J-10,367
- Journal Information:
- Journal of Colloid and Interface Science, Vol. 585; ISSN 0021-9797
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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