Practical polyrotaxane synthesis using capillary tubes based on active-threading mechanism

Abstract We introduce a practical strategy for synthesis of polyrotaxanes (PRs) wusing a capillary tube as a flowing reaction vessel. Poly(ethylene glycol) (PEG) effectively threads into γ-cyclodextrin (γ-CD), overcoming the restrictions of host–guest interactions established under thermodynamic equilibrium. The influence of the motion of the solution on the host–guest interactions are investigated by changing capillary diameter and length, and flow rates. Thinning the flowing solution increases the number of CDs participating in the formation of PRs and increases the threading rate. A thin flowing solution in a capillary tube less than 300 µm diameter is needed to accelerate host-guest interaction in a flow. The formation of a dynamic multi-layer structure in a thinner flow would play a crucial role to convert the linear motion of the solution to host–guest interactions.