Synthesis and self-assembly behavior of four-arm poly(ethylene oxide)-b-poly(2-(diethylamino)ethyl methacrylate) star block copolymer in salt solutions |
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Authors: | He E Ravi P Tam K C |
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Institution: | School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798. |
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Abstract: | A well-defined block copolymer consisting of four-arm poly(ethylene oxide)-b-poly(2-(diethylamino)ethyl methacrylate) (four-arm PEO56-b-PDEAEMA74) was synthesized by atom transfer radical polymerization. The pH-responsive self-assembly behavior was examined by potentiometric titration, surface tensiometry, laser light scattering, and transmission electron microscopy over the course of dissociation by the addition of a base or acid. The apparent hydrodynamic radius (Rh) of the micelle increased from 21 to 56 nm when the degree of protonation of the amine groups was increased from 0 to 0.5 in 0.01 M NaCl solution. In higher concentration NaCl solution, the micelle shrank due to the electrostatic charge screening of the protonated DEAEMA groups. At low pH, the micelles dissociated into unimers. |
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