A new type of polymer-assisted self-assembly of
nanospheres at a water-air interface was uncovered. By adding
merely 1-3 ppm of polyethylene oxide in the water, the
polystyrene nanospheres, applicable to diameters ranging
from 100 nm to 1 ?m, were found to gradually move closer
to each other and eventually form a close-packed structure
confirmed from its diffraction pattern. As it turns out, polyethylene oxides are adsorbed onto the surface of polystyrene
nanospheres, giving rise to the effective screening of coulomb
repulsive force between nanospheres followed by the onset of polymer-bridging effect as demonstrated from the strong
suppression of Brownian motion. The resulting monolayer of close-packed polymer/nanospheres hybrid at the water-air
interface with area size more than 1 cm2 are robust and can be transferred to a substrate of any kind without serious breaking
due to surface tension tearing. Our finding may provide a further extension to the scope of nanosphere lithography
technique.