Polymer Multilayer Particles:  A Route to Spherical Dielectric Resonators

Polymer multilayer particles with radial variation in refractive index can possess a photonic band gap and therefore can be used as spherical dielectric resonators (SDRs). We synthesized multilayer microspheres with morphology “predesigned” by modeling their scattering cross section. The particles had a polystyrene core and four 150 ± 20 nm thick alternating layers of polystyrene and poly(trifluoroethyl methacrylate) which were used as a high and a low refractive index counterpart, respectively. We confirmed the morphology of microspheres by transmission electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy. We undertook a further step in increasing refractive index contrast between the layers by copolymerizing styrene with vinylcarbazole.