Dense and square lattice-free colloid crystals of highly charged monodisperse latex particles on 3-aminopropyl trimethoxysilane-modified glass substrate

Two- and three-dimensional colloid arrays are fabricated using highly charged, monodisperse poly(styrene/sodium p-styrene sulfonate) particles and 3-aminopropyl trimethoxysilane (APTMS)-modified glass substrates at 20 °C. The colloidal array patterns were investigated by SEM, AFM, and UV-visible analyses, and the pattern on the APTMS-modified glass substrate shows a denser packing and square lattice-free pattern without any crevices, as compared with that of cleaned, bare glass substrates. The adhesion force curves obtained from AFM analysis proved a negligible attractive force between APTMS and the poly(St/NaSS) particles. The APTMS layer guaranteed the free-slipping condition to prevent scattered pinnings of drawing particles into the nuclei. Consequently, the free-slipping led to a denser hexagonal close packing and particle deformation by a stronger capillary force arising from the reduced interstices among the particles. As a result, a dense (packing density ∼ 0.80) fcc (or hcp) packing and narrower stop bands were obtained.