pH-Responsive amphiphilic branched copolymers were prepared from poly(ethylene glycol) methyl ether methacrylate (PEGMA), 2-(diethylamino)ethyl methacrylate (DEAEMA), 2-(tert-butylamino)ethyl methacrylate (tBAEMA), and ethylene glycol dimethacrylate (EGDMA) utilizing a thiol-modified free radical polymerization. The molecular structures of copolymers were confirmed by proton nuclear magnetic resonance spectroscopy (1H NMR) and triple-detection gel permeation chromatography (tri-GPC). The aqueous solution behaviors of the obtained copolymers were investigated by dynamic light scattering (DLS). The DLS data showed that about 16 nm polymer particles comprising of hydrophobic poly(tert-butylamino)ethyl methacrylate (PtBAEMA) and poly(diethylaminoethyl methacrylate (PDEAEMA) core, hydrophilic PEGMA corona were formed above pH 8. With the decrease of pH from 8 to 6, a dramatic increase in the hydrodynamic radius of polymer particles from 16 nm to 130 nm was observed resulting from the protonation of the PDEAEMA segment. Moreover, in vitro drug release behaviors of the resulting polymer assemblies at different pH values were also investigated to evaluate their potential as sustained release drug carriers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42183.
