Polyether-based polyrotaxane synthesis with controlled β-cyclodextrin threading ratio

An effective one-pot polyrotaxane synthesis with control of the threading ratio is realized. 2,5-Bis(chloromethyl)-4-methoxy-1-octoxybenzene (PMOC) is condensed with a starting rotaxane consisting of a bisphenol A salt threaded into β-cyclodextrin (βCD), to lead to a βCD-threaded polyether. We demonstrate that the threading ratio of βCD on the polyether chain (ratio between the polymer repeat units and the βCD in polyrotaxane) can be varied from zero to unity depending on two parameters: the reactant concentration and the bulkiness of the counter-ion stopper in the starting rotaxane.