INS2-1569
Molecular Mapping and Controlled Assembly of Crystallization-Driven Conjugated-Polymer Nanowires via Cryogenic and In-situ Liquid-Phase TEM
Topic
S2. High-End Characterization/Polymer Physics/Properties
When and Where
Sep 29, 2026
17:05 - 17:30
Room 103
Session Chairs
Joe PATTERSON
Presenter(s)
Eunji Lee (Gwangju Institute of Science and Technology)
Co-Author(s)
Abstract
Controlling the nanoscale morphology of conjugated polymers (CPs) is central to the performance of organic and stretchable electronics, yet the molecular-scale interactions that govern their crystallization-driven self-assembly (CDSA) into one-dimensional nanowires (NWs) have been difficult to visualize and control at the same time. Here we present a cryogenic and in-situ liquid-phase transmission electron microscopy (TEM) platform that resolves, and enables control over, the full seeding-and-growth hierarchy of polythiophene-based CP NWs. First, simply blending a polythiophene-based CP with an electron-accepting molecular dopant in a single good solvent triggers integer charge transfer, driving spontaneous pi-pi stacking, seed formation, and 1D growth without any solvent or temperature control. In-situ liquid-phase TEM directly visualizes this stepwise seed-and-growth mechanism in real time, while kinetic analysis of nucleation and elongation yields parameters for tuning the assembly through charge transfer. Second, because CDSA inevitably yields heterogeneous mixtures of crystalline NWs and amorphous tie chains, we introduce density-driven differential sedimentation to fractionate the suspension, and develop a cryo-TEM quantitative morphological mapping framework that resolves backbone tilt, width uniformity, and lattice coherence at the single-NW level. This reveals that local cofacial pi-pi packing is preserved across fractions, whereas long-range lamellar coherence and transport-favorable end-on chain orientation concentrate in the crystalline sediment. Recombining the fractions at controlled ratios programmably tunes the mobility-to-stretchability trade-off without chemical modification, and generalizes to coaxial donor-acceptor hybrid NWs. Together, correlated cryo- and in-situ TEM turn CP molecular interactions into directly observable and programmable design parameters, from charge-transfer-driven nucleation to single-NW structural control.
