Ionic depletion at the crystalline Gibbs layer of PEG-capped gold nanoparticle brushes at aqueous surfaces

Wenjie Wang, Honghu Zhang, Surya Mallapragada, Alex Travesset, David Vaknin
2017 PHYSICAL REVIEW MATERIALS  
In situ surface-sensitive x-ray diffraction and grazing incidence x-ray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolatedpolyethylene-glycol-capped gold nanoparticle (PEG-AuNP) solutions. Induced by the addition of salts (i.e., Cs2SO4) to PEG-AuNPs solutions, two-dimensional hexagonal lattices of PEG-AuNPs form spontaneously at the aqueous surfaces, as is demonstrated by x-ray reflectivity and grazing
more » ... ty and grazing incidence small-angle x-ray scattering. By taking advantage of element specificity with the GIXFS method, we find that the cation Cs+ concentration at the crystalline film is significantly reduced in parts of the PEG-AuNP film compared with that in the bulk. In situ surface-sensitive x-ray diffraction and grazing incidence x-ray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolatedpolyethylene-glycol-capped gold nanoparticle (PEG-AuNP) solutions. Induced by the addition of salts (i.e., Cs 2 SO 4 ) to PEG-AuNPs solutions, two-dimensional hexagonal lattices of PEG-AuNPs form spontaneously at the aqueous surfaces, as is demonstrated by x-ray reflectivity and grazing incidence small-angle x-ray scattering. By taking advantage of element specificity with the GIXFS method, we find that the cation Cs + concentration at the crystalline film is significantly reduced in parts of the PEG-AuNP film compared with that in the bulk.
doi:10.1103/physrevmaterials.1.076002 fatcat:eprcpafjijhitko4i46xljpqdi