Bulk Assembly of Intrachain Folded Aromatic Polyamides Facilitating Through-Space Charge Transport Phenomenon

Significant progress has been made in replicating the secondary structures of biomolecules, but more work is needed to mimic their higher-order structures essential for complex functions. This study entails designing periodically grafted aromatic polyamides to explore the possibility of mimicking higher-order structures and related functions. The incompatibility between aromatic hydrocarbon and grafted polyethylene glycol (PEG) chains is utilized for immiscibility-driven phase segregation and their bulk assemblies. Additionally, these polyamides can induce an intrachain folded structure, promoting an organized arrangement of π-surfaces in phase-segregated domains, distinguishing this research from conventional polymer phase separation. Notably, the incorporation of aromatic guest molecules results in significant enhancements in the structural coherence of these aromatic polyamides. Like structural characterizations, the host-guest complex exhibits superior charge transport potential across the ordered π-domains than the host polymer alone. The vertical charge transport setup yields a current density of ≈10^-4 A cm^{- 2}, while the lateral currents in a horizontal setup (≈10^-10 A) are insignificant, indicating a preferential alignment of π-domains within the bulk structure. Additionally, substrate surface chemistry influences the orientation of the π-folded domains, with hydrophilic glass substrates resulting in higher lateral currents (≈10^-5 A) compared to unmodified glass, highlighting the potential of these materials for electronic applications.