The effect of molecular weight on light scattering of photonic poly styrene-block-poly-2-vinyl pyridine nano-structure

Abstract

One dimensional structures often limit viewing angle as well as reflection color changes [1]. We report a simple strategy to fabricate the ellipsoidal block copolymer nanoparticles [2], which have a wider viewing angle. The photonic crystals were made with the polystyrene-block-poly-2-vinyl pyridine (PS-b-P2VP) dispersed in chloroform. When the PS-b-P2VP was sonicated in polyvinyl alcohol (PVA), it became white emulsion. The photonic crystals were formed by self-assembly of block copolymers. We observed particle structure variations(color of viewing angle) according to the difference in molecular weight, which were 57k-57k, 75k-66.5k. The swelling and nature of light scattering from structured particles changed by the addition of ethanol. The color was measured by color-difference meter [3-5]. The particles with low molecular weight showed the short wavelength reflection [6-9].