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Title: Two-Dimensional Crystallization of Poly( N-isopropylacrylamide)-Capped Gold Nanoparticles

Abstract

Surface-sensitive X-ray reflectivity and grazing incidence small-angle X-ray scattering reveal the structure of polymer-capped-gold nanoparticles (AuNPs that are grafted with poly(N-isopropylacrylamide); PNIPAM–AuNPs) as they self-assemble and crystallize at the aqueous suspension/vapor interface. Citrate-stabilized AuNPs (5 and 10 nm in nominal diameter) are ligand-exchanged by 6 kDa PNIPAM-thiol to form corona brushes around the AuNPs that are highly stable and dispersed in aqueous suspensions. Surprisingly, no clear evidence of thermosensitive effect on surface enrichment or self-assembly of the PNIPAM–AuNPs is observed in the 10–35 °C temperature range. However, addition of simple salts (in this case, NaCl) to the suspension induces migration of the PNIPAM–AuNPs to the aqueous surface, and above a threshold salt concentration, two-dimensional crystals are formed. In conclusion, the 10 nm PNIPAM–AuNPs form a highly ordered single layer with in-plane triangular structure, whereas the 5 nm capped NPs form short-range triangular structure that gradually becomes denser as salt concentration increases.

Authors:
 [1];  [1];  [2];  [3]; ORCiD logo [4]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States). Division of Materials Sciences and Engineering
  2. Univ. of Chicago, IL (United States). NSF’s ChemMatCARS
  3. Ames Lab., Ames, IA (United States). Dept. of Materials Science and Engineering
  4. Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1464476
Report Number(s):
IS-J-9723
Journal ID: ISSN 0743-7463
Grant/Contract Number:  
AC02-07CH11358; AC02-06CH11357; CHE-1346572
Resource Type:
Accepted Manuscript
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 34; Journal Issue: 28; Journal ID: ISSN 0743-7463
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Wang, Wenjie, Lawrence, Jack J., Bu, Wei, Zhang, Honghu, and Vaknin, David. Two-Dimensional Crystallization of Poly(N-isopropylacrylamide)-Capped Gold Nanoparticles. United States: N. p., 2018. Web. doi:10.1021/acs.langmuir.8b01042.
Wang, Wenjie, Lawrence, Jack J., Bu, Wei, Zhang, Honghu, & Vaknin, David. Two-Dimensional Crystallization of Poly(N-isopropylacrylamide)-Capped Gold Nanoparticles. United States. doi:10.1021/acs.langmuir.8b01042.
Wang, Wenjie, Lawrence, Jack J., Bu, Wei, Zhang, Honghu, and Vaknin, David. Wed . "Two-Dimensional Crystallization of Poly(N-isopropylacrylamide)-Capped Gold Nanoparticles". United States. doi:10.1021/acs.langmuir.8b01042. https://www.osti.gov/servlets/purl/1464476.
@article{osti_1464476,
title = {Two-Dimensional Crystallization of Poly(N-isopropylacrylamide)-Capped Gold Nanoparticles},
author = {Wang, Wenjie and Lawrence, Jack J. and Bu, Wei and Zhang, Honghu and Vaknin, David},
abstractNote = {Surface-sensitive X-ray reflectivity and grazing incidence small-angle X-ray scattering reveal the structure of polymer-capped-gold nanoparticles (AuNPs that are grafted with poly(N-isopropylacrylamide); PNIPAM–AuNPs) as they self-assemble and crystallize at the aqueous suspension/vapor interface. Citrate-stabilized AuNPs (5 and 10 nm in nominal diameter) are ligand-exchanged by 6 kDa PNIPAM-thiol to form corona brushes around the AuNPs that are highly stable and dispersed in aqueous suspensions. Surprisingly, no clear evidence of thermosensitive effect on surface enrichment or self-assembly of the PNIPAM–AuNPs is observed in the 10–35 °C temperature range. However, addition of simple salts (in this case, NaCl) to the suspension induces migration of the PNIPAM–AuNPs to the aqueous surface, and above a threshold salt concentration, two-dimensional crystals are formed. In conclusion, the 10 nm PNIPAM–AuNPs form a highly ordered single layer with in-plane triangular structure, whereas the 5 nm capped NPs form short-range triangular structure that gradually becomes denser as salt concentration increases.},
doi = {10.1021/acs.langmuir.8b01042},
journal = {Langmuir},
number = 28,
volume = 34,
place = {United States},
year = {2018},
month = {6}
}

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