Aggregation Behavior of Copolymer Containing Sulfobetaine Structure in Aqueous Solution

Complementary light scattering and synchrotron small-angle X-ray scattering studies of the micelle-to-unimer transition of polysulfobetaines

AB and ABA di- and triblock copolymers where A is the hydrophilic poly(oligoethylene glycol methacrylate) (POEGMA) block and B is a thermo-responsive sulfobetaine block [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (PDMAPS) were synthesised by aqueous RAFT polymerisation with narrow dispersity (ĐM ≤ 1.22), as judged by aqueous SEC analysis. The di- and triblock copolymers self-assembled in salt-free water to form micelles with a PDMAPS core and the self-assembly of these polymers was explored by SLS and TEM analysis. The micelles were shown, by DLS analysis, to undergo a micelle-to-unimer transition at a critical temperature, which was dependent upon the length of the POEGMA block. Increasing the length of the third, POEGMA, block decreased the temperature at which the micelle-to-unimer transition occurred as a result of the increased hydrophilicity of the polymer. The dissociation of the micelles was further studied by SLS and synchrotron SAXS. SAXS analysis revealed that the micelle dissociation began at temperatures below that indicated by DLS analysis and that both micelles and unimers coexist. This highlights the importance of using multiple complementary techniques in the analysis of self-assembled structures. In addition the micelle-to-unimer morphology transition was employed to encapsulate and release a hydrophobic dye, Nile Red, as shown by fluorescence spectroscopy.

Polysulfobetaine-based diblock copolymer nano-objects via polymerization-induced self-assembly

A zwitterionic polysulfobetaine-based macro-CTA is used for the synthesis of spheres, worms or vesiclesviaaqueous RAFT dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA). These new diblock copolymer nano-objects exhibit high tolerance of added salt.

Rheological behavior of hydrophobically modified polysulfobetaine methacrylate aqueous solution

Polysulfobetaine methacrylate (PSBMA) that was hydrophobically modified with methacrylic acid 2,3-epoxypropyl ester (GMA) was synthesized via micellar copolymerization method. Viscosity of the hydrophobically modified PSBMA solution was sensitive to added salt concentration.