Enhancement of thermal stability of structural color by the substituent effect in polyhedral oligomeric silsesquioxane in block copolymers

Abstract

We prepared high-molecular-weight block copolymers (BCPs) composed of polystyrene (PS) brush blocks and polyhedral oligomeric silsesquioxane (POSS)-tethered polynorbornenes with variable composition ratios. By changing the substituents at the vertex of POSS from isobutyl groups to cyclopentyl ones, we evaluated the substituent effect on structural color and thermal stability against annealing. The BCPs modified with isobutyl groups showed clear structural color, while color changes were observed after annealing. By replacing to cyclopentyl groups, structural color was also presented, and improvement of thermal resistance was observed by heating. From the series of thermal analyses, it was proposed that thermal enhancement of cyclopentyl-substituted POSS domains could be responsible for the improvement of thermal stability of structural color.