The Polymer Society of Korea

Abstract

We fabricated uniform block copolymer (BCP) photonic particles using PS-<em>b</em>-P2VP and bromine-functionalized quaternizing additives, including 1-bromooctane (BO), 8-bromooctylbenzene (BOB), 8-bromooctylnaphthalene (BON) and 10-bromodecylbenzene (BDB). Among these, BOB showed the most effective improvement in domain spacing and was selected for photonic particle fabrication. Uniform emulsions were produced via microfluidic chips, and BCPs are self-assembled by solvent evaporation to form photonic particles. These particles showed clear structural colors, red-shifting from blue to red as the mole ratio between additive and 2VP units increased. The quaternization of additives with 2VP units altered the hydrophilicity of P2VP domains, leading to an increase in domain spacing. Ultra-microtoming analysis confirmed that the expanded domain spacing is well consistent with the observed reflective colors. Also, the structural color of the particles was reversible under varying pH conditions.