Discrete Giant Polymeric Chain with Precise Sequence and Regio-configuration: A Concise Multiblock Model System

Abstract

The vastly expanding chemical and architectural parameter space of multiblock copolymers brings both opportunities and challenges for tailoring the structure and properties of a synthetic polymer. In this study, we reported a precise and concise multiblock model system to amplify the subtle structural variations and resolve the underlying phase principles. A series of giant polymeric chains based on polyhedral oligomeric silsesquioxane nanoparticles with an exact block number, regio-configuration, and sequence were designed and prepared. A close scrutiny of these sequence-/regio-isomers revealed that the interplay of geometric constraints, regio-configurations, and collective interactions dictates the self-assembled structures. Zigzag-packed lamellae with the layer normal perpendicular to the backbone were observed for the alternating chains, while a head-to-head arrangement with the lamellar normal along the chain direction was recognized in the case of block chains. Due to the geometric constraint, the alternating chains were exceedingly sensitive to the regio-regularity, leading to dramatically different phase stabilities. This work reveals the critical contribution of the block sequence and regio-configuration to phase behaviors, providing deeper insights toward rational structural engineering of multiblock copolymers.