"Micromolding in Capillaries" for Making Ordered Polymer Beads Crystal Array

An effective procedure was demonstrated to crystallize spherical micro-beads into ordered arrays by means of “micromolding in capillaries (MIMIC)”in soft lithography. Patterned microstructures of polystyrene micro-beads were formed by molding in enclosed continuous channels formed by the conformal contact between a solid support and an elastomeric mold whose surface had been patterned with a relief structure having micrometer-scale dimensions. Awater suspension of PS micro-beads filled these channels by capillary action and was allowed to solidify. The mold was then removed. The results showthat the polystyrene micro-beads can be assembled in thisway, and the order and tight two-dimensional andQuasi-three dimensional crystals array can be obtained atthe exit end of capillaries. Theweight concentration of the polymer latex, the dimension of the noncircular capillaries and the environmental temperature are three main factors to govern the ordering of polymer micro-beads.