LAUSR

Conformational changes in macromolecules significantly affect their functions and assembly into high‐level structures. Despite advances in theoretical and experimental studies, investigations into the intrinsic conformational variations and dynamic motions of single macromolecules remain challenging. Here, liquid‐phase transmission electron microscopy enables the real‐time tracking of single‐chain polymers. Imaging linear polymers, synthetically dendronized with conjugated aromatic groups, in organic solvent confined within graphene liquid cells, directly exhibits chain‐resolved conformational dynamics of individual semiflexible polymers. These experimental and theoretical analyses reveal that the dynamic conformational transitions of the single‐chain polymer originate from the degree of intrachain interactions. In situ observations also show that such dynamics of the single‐chain polymer are significantly affected by environmental factors, including surfaces and interfaces.