Thermoresponsive Reversible Unimer Micelles of Amphiphilic Fluorinated Copolymers |
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Authors: | Elisa Guazzelli Elena Masotti Manfred Kriechbaum Frank Uhlig Giancarlo Galli Elisa Martinelli |
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Institution: | 1. Department of Chemistry and Industrial Chemistry, University of Pisa, Pisa, 56124 Italy;2. Institute for Inorganic Chemistry, Graz University of Technology, Graz, 8010 Austria |
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Abstract: | Amphiphilic fluorinated copolymers PEGMAx-co-FAy and TEGMAx-co-FAy are prepared by activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP). All polymers present a reversible thermoresponsive lower critical solution temperature-type behavior, and a cloud point temperature (Tc) in the range of 30–60 °C strictly dependent on the length of the oxyethylene side chain, the content of the hydrophobic counits, and the concentration of the solution. Combined small angle X-ray scattering (SAXS) and dynamic light scattering measurements are used to study the self-assembly behavior in water, organic solvents (tetrahydrofuran THF] and dimethylformamide DMF]), and a fluorinated solvent (hexafluorobenzene HFB]). SAXS confirms the formation of compact-globular single-chain self-folded unimer micelles in water below Tc, which generally presents small hydrodynamic diameters (Dh ≤ 8 nm) as a result of the folding of the hydrophobic perfluorohexylethyl acrylate counits. The copolymers are also able to form reverse unimer micelle in HFB. The copolymers are not able to self-assemble in unimer micelles in THF or DMF solutions, in which they adopt conventional random coil conformations. |
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Keywords: | amphiphilic polymers lower critical solution temperature reverse micelles single-chain nanoparticles small angle X-ray scattering thermoresponsive polymers |
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