Open AccessThe mechanism of self-assembly of polystyrene submicrospheres at water-air interface
Author(s) -
Xiaodong Wang,
Dongdong Peng,
Shengli Chen,
Guiyun Yi
Publication year - 2007
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.56.1831
Subject(s) - wetting , contact angle , spheres , materials science , polystyrene , evaporation , colloid , suspension (topology) , aqueous suspension , capillary action , chemical engineering , aqueous solution , nanotechnology , composite material , chemistry , thermodynamics , physics , polymer , engineering , mathematics , astronomy , homotopy , pure mathematics
The mechanism of polystyrene submicrospheres assembling in aqueous suspension was studied systemically. During the evaporation of solvent, the PS spheres were transported to the water-air inter-surface, where these spheres self-assemble into colloidal crystal through the capillary force between the particles at water-air interface. The wettability of the PS spheres at the water-air interface changes from complete wetting to partial wetting and finally to non-wetting with the evaporation of water, so that the contact angle between the PS spheres and water increases gradually. The experiment showed that only after the contact angle reached a critical value θ′critical, could the PS sphere-assembly occur. The critical value θ′critical obtained from the Wenzel equation was greater than the measured value θcritical22° because the surface of the PS colloidal crystal was “regularly” coarse. The change of the PS spheres at water-air interface from the hydrophilic to hydrophobic is essential for the PS spheres to assemble into colloidal crystals.