Prolate and Temperature-Responsive Self-Assemblies of Amphiphilic Random Copolymers with Perfluoroalkyl and Polyoxyethylene Side Chains in Solution

Two amphiphilic random copolymers, PEGMAx-co-FAy (x=90 and 70mol%), are synthesized by ATRP and their solutions are investigated as a function of solvent, concentration, and temperature by DLS and SANS analyses. Both copolymers self-assemble in nanostructures by single-chain folding in water solutions over a wide range of temperatures. The values of the DLS hydrodynamic radius and the SANS radius of gyration are found to be approximate to 4nm and approximate to 3.4-3.7nm, respectively. Moreover, SANS shows the self-folded nanoassemblies to be prolated spheroids with a ratio of polar/equatorial axes of approximate to 5:1 for PEGMA90-co-FA10 and approximate to 2:1 for PEGMA70-co-FA30. On heating above a critical temperature T-c, multichain microassemblies are formed that revert back to nanoassemblies on cooling below T-c. This temperature-responsive transition is fully and sharply reversible.