Synthesis and Self-Assembly of pH-Responsive Amphiphilic Poly(dimethylaminoethyl methacrylate)-block-Poly(pentafluorostyrene) Block Copolymer in Aqueous Solution

Authors

  • Beng H. Tan,

    1. Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
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    • Both authors contributed equally to this work.

  • Chakravarthy S. Gudipati,

    1. Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
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    • Both authors contributed equally to this work.

  • Hazrat Hussain,

    1. Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
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  • Chaobin He,

    1. Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
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  • Ye Liu,

    Corresponding author
    1. Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
    • Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore.
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  • Thomas P. Davis

    Corresponding author
    1. Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
    2. Centre for Advanced Macromolecular Design (CAMD), School of Chemical Sciences and Engineering, UNSW, Sydney, NSW 2052, Australia
    • Centre for Advanced Macromolecular Design (CAMD), School of Chemical Sciences and Engineering, UNSW, Sydney, NSW 2052, Australia.
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Abstract

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, Nagg ≈ 30 where the dense PPFS core is surrounded by dangling PDMAEMA chains as the micelle corona. The hydrodynamic radii, Rh 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 Rh. However, the radius of gyration, Rg remains independent of pH as the dense PPFS cores predominate.

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