Abstract: A new methodology for template-directed polymerization is described which is suitable for easy microbead formation. Cationic polymerization of a bis-epoxy silicone monomer by a diaryliodonium salt photoinitiator was found to occur fast enough to polymerize the droplets of an aerosol spray of the monomer, photoinitiator, and template in flight. Symmetric microbeads averaging 31 mu m in diameter were produced and captured by electrostatic precipitation. The effect of numerous functional groups on the rate of polymerization is discussed. Nitrogenous bases were found to be detrimental to polymer bead formation, as were certain carboxylic acids. Beads imprinted with morphine analogue thebaine displayed stronger molecular recognition properties for thebaine than did nonimprinted beads. However, both thebaine-templated and nonimprinted beads retained similar amounts of the thebaine derivative 17,18- bis(methoxycarbonyl)-6,14-ethenocodeine methyl ether