Homogeneous Polymer Blend Microparticles With a Tunable Refractive Index

Barnes, M. D., C.-Y. Kung, N. Lermer, K. Fukui, B. G. Sumpter, D. W. Noid, and J. U. Otaigbe

Chemical and Analytical Sciences Division

Oak Ridge National Laboratory, Oak Ridge, TN, USA

Abstract

We show that homogeneous polymer blend microparticles can be prepd. in situ from droplets of dil. soln. of codissolved polymers. Provided that the droplet of soln. is small enough (<10 m m), solvent evapn. is rapid enough to inhibit phase sepn. Thus the polymers that are being mixed need not be miscible, which greatly enhances the applicability of the technique. From anal. of two-dimensional Fraunhofer diffraction (angular scattering) patterns, we show that both the real and the imaginary parts of the refractive index can be tuned by adjustment of the relative wt. fractions of polymers in soln.