Stable Helical Assembly of Propellane-Based Polymers and Nanotube Composites

The integration of chirality into organic semiconductors offers promising avenues for next-generation information storage and spintronic technologies. Chiral conjugated polymers, particularly polyfluorenes, have emerged as attractive candidates due to their favorable optoelectronic properties and potential to support phenomena such as circularly polarized luminescence (CPL), electrical magnetochiral anisotropy (eMChA), and chirality-induced spin selectivity (CISS). However, achieving robust and persistent chiral order in these systems remains challenging as their helical conformations are often sensitive to processing conditions, aggregation, and film morphology. Here, we report a series of chiral polyfluorene copolymers incorporating [4.3.3] propellane units that serve as rigid, three-dimensional scaffolds to stabilize supramolecular helicity. These propellane-functionalized polymers exhibit enhanced chiroptical responses in both solution and thin-film states, including amplified circular dichroism signals at reduced film thickness. Furthermore, we demonstrate that these materials form stable composites with single-walled carbon nanotubes, yielding well-dispersed and semiconducting carbon nanotube networks suitable for organic field-effect transistor (OFET) applications. Our findings present a molecular design strategy to improve chiral order and device integration in conjugated polymer systems, with implications for the future development of spintronic and optoelectronic devices.