Impact of Amino-Functionalization on the Response of Poly(ethylene glycol) (PEG) to External Stimuli.

It is shown that amino-functionalization of poly(ethylene glycol) (PEG) with the comonomer ,-diethyl glycidyl amine (DEGA) triggers the emergence of extraordinary stimuli responsiveness and phase behavior of PEG. In dependence of the solution pH, tapered PEG--PDEGA exhibits a highly cooperative two-step inverse phase transition with respect to temperature. The polymer forms dispersed metastable nanoglobules in the medically relevant temperature range around human body temperature. Independently, cloud points can be adjusted between 40 and 90 °C via the pH of the solution. Changing the polymer architecture to a block structure, in pronounced contrast, the polymer exhibits a gradual growth of micelles with temperature until macroscopic aggregation takes place. Thus, through amino-functionalization of PEG, one can precisely control the temperature range and the mechanism of the inverse phase transition of this promising polymer-therapeutics candidate by adjusting solution conditions and polymer topology.