Tuning the Diameter of Supramolecular Nanocylinders: Balancing Long and Short Polymer Arms for Optimized Self‐Assembly

Nanocylinders find applications in biology, catalysis, and material science due to their high aspect ratio and nanometric diameter, granting them a high specific area. They can be formed by supramolecular assembly in solution of polymers decorated by stickers promoting directional assembly. Controlling the dimensions of nanocylinders impacts their applicative properties. Many strategies exist to tune their length, but much fewer to tune their diameter. We address this point here by synthesizing water‐soluble polymers of different lengths end‐functionalized by hydrogen bonding tris(urea) stickers. It is shown through a combination of light/neutron scattering experiments and cryo‐transmission electron microscopy that short polymer arms (DP ≤ 80) produce thin (d = 10 nm) and long (L > 500 nm) nanocylinders, whereas longer polymer arms (DP ≥ 500), required to significantly increase d, inhibit self‐assembly due to the strong entropic penalty caused by their stretching. A compromise to control d is to mix a few long arms, which increase d, with a sufficient amount of short arms, which alleviate the entropic penalty and maintain high L. This approach proposes a straightforward way to tune the specific area of nanocylinders—a key parameter for applications in catalysis, emulsion stabilization, or interactions with biological materials.