Backbone-thermosensitive hyperbranched polyethers were synthesized in one step by the cationic ring-opening copolymerization of tetrahydrofuran and glycidol. The hyperbranched polyethers had soft polytetrahydrofuran segments in the backbones

and their structures were characterized by quantitative 13C-NMR. Then the degree of branching and the ratio of glycidol units incorporated into the structure were also calculated. The molecular weight and molecular weight distribution were characterized by size exclusion chomatography-multi-angle laser light scattering (SEC-MALLS). The thermoresponsive phase transition behavior of the hyperbranched polyether in aqueous solution was intensively investigated by UV-Vis spectrometer equipped with a thermocell. It was found that the UV transmittance of the aqueous solution of the hyperbranched polyethers decreased dramatically when the temperature was increased above LCST

but the balance of phase transition was very slow and the phase transition time was up to 30 min. At the same time

the kinetics of phase transition and final value of UV transmittance were dependent on the temperature

which suggested that the phase transition process could be effectively controlled by adjusting the temperature. TEM inspection showed that the hyperbranched polyethers in aqueous solution could assemble to form micelles at low temperatures. And then

the micelles gradually aggregated as the temperature was increased above LCST

which caused the slow and controlled phase transition process.