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Synthesis and Self‐Assembly of pH‐Responsive Amphiphilic Poly(dimethylaminoethyl methacrylate)‐ block ‐Poly(pentafluorostyrene) Block Copolymer in Aqueous Solution
Author(s) -
Tan Beng H.,
Gudipati Chakravarthy S.,
Hussain Hazrat,
He Chaobin,
Liu Ye,
Davis Thomas P.
Publication year - 2009
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200800799
Subject(s) - micelle , copolymer , hydrodynamic radius , dynamic light scattering , polymer chemistry , amphiphile , materials science , methacrylate , aqueous solution , polymerization , radius of gyration , dispersity , chemical engineering , chemistry , polymer , organic chemistry , nanoparticle , nanotechnology , engineering , composite material
We report the synthesis of a novel pH‐responsive amphiphilic block copolymer poly(dimethylaminoethyl methacrylate)‐ block ‐poly(pentafluorostyrene) (PDMAEMA‐ b ‐PPFS) using RAFT‐mediated living radical polymerization. Copolymer micelle formation, in aqueous solution, was investigated using fluorescence spectroscopy, static and dynamic light scattering (SLS and DLS), and transmission electron microscopy (TEM). DLS and SLS measurements revealed that the diblock copolymers form spherical micelles with large aggregation numbers, N agg ≈ 30 where the dense PPFS core is surrounded by dangling PDMAEMA chains as the micelle corona. The hydrodynamic radii, R h of these micelles is large, at pH 2–5 as the protonated PDMAEMA segments swell the micelle corona. Above pH 5, the PDMAEMA segments are gradually deprotonated, resulting in a lower osmotic pressure and enhanced hydrophobicity within the micelle, thus decreasing the R h . However, the radius of gyration, R g remains independent of pH as the dense PPFS cores predominate.