6533b831fe1ef96bd1298d26

RESEARCH PRODUCT

Well-Defined Multi-Amino-Functional and Stimuli-Responsive Poly(propylene oxide) by Crown Ether Assisted Anionic Ring-Opening Polymerization

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Multi-amino-functional poly(propylene oxide) (PPO) copolymers were synthesized by the anionic ring-opening copolymerization (AROP) of N,N-diethyl glycidyl amine (DEGA) and propylene oxide (PO). A solvent free synthesis route using potassium counterions and crown ether for the AROP enabled controlled (co)polymerization with full conversion. The strategy provided access to PPO-b-PDEGA block copolymers, statistical PPO-co-PDEGA copolymers, and, for the first time, PDEGA homopolymer. Molecular weights in the range of 1400 to 4200 g/mol (Mn) and dispersities (Mw/Mn) below 1.1 were obtained. Both the kinetics and resulting microstructure of the statistical copolymerization were investigated by in situ 1H NMR spectroscopy, revealing reactivity ratios of rPO = 1.7 and rDEGA = 0.9. The polyethers exhibit thermoresponsive behavior in aqueous solution, showing cloud points in the range 14–57 °C under neutral conditions. Because of the amine groups, the copolymer structures are strongly affected by the pH of the solu...