Shape Amphiphiles Based on POSS-Polymer Conjugates: Systematic Molecular Design, Sequential Click Synthesis, and Diverse Self-Assembly Behaviors

The ordered structures generated by self-assembly of various nano-materials have attracted great amount of interests due to their potentials in advanced material design via the “bottom-up” approach. Shape amphiphiles, constructed by the chemical integration of molecular building blocks with distinct shapes and competing interactions, emerge as a novel class of nano-materials. In this presentation, the molecular design and synthesis of a library of shape amphiphiles with precisely defined structures based on conjugates of functionalized polyhedral oligomeric silsesquioxanes (POSS) and polystyrene (PS) are reported. The development of a “sequential click” approach and the utilization of a series of “click adaptor” molecules facilitate the modular and efficient precision synthesis and the feasible structural diversification of molecular architectures for a systematic investigation. It was subsequently revealed that in the bulk state, driven by the nano-phase separation between the POSS cages and the polymer chains, POSS-based shape amphiphiles can self-assemble into various kinds of ordered phases with sub-10 nm feature sizes, depending on the relative volume fraction of the two components. Moreover, by tuning the molecular architectures of POSS-based shape amphiphiles, some rare phases can be observed, such as a highly asymmetric lamellar phase and an unusual A15 cubic phase. Therefore, POSS-based shape amphiphiles provide a versatile platform for engineering structures with sub-10 nm feature sizes