Effect of neutral polymers on the ordering of monodispersed polystyrene spheres

Abstract

Ordered lattice structures, face-centred cubic (f.c.c.) lattices, are analysed by the reflection spectrum measurements of monodispersed polystyrene latex spheres in the presence of neutral water-soluble polymers. The polymers are poly(vinyl alcohol)(PVA), poly(ethylene glycol)(PEG), poly(vinyl pyrrolidone)(PVP), hydroxypropylcellulose (HPC), and poly(acrylamide)(PAA_m). The intersphere distances in the ordered phase are found to be in the order PEG > PVA > nonpolymer > PVP ≈ HPC > PAA_m for the same latex concentration. This effect of neutral polymers is explained by intersphere repulsion from the electrical double-layer interaction (Debye screening length), which is influenced by adsorption of the polymer on the latex surface due to hydrophobic and/or dipole–dipole interactions.