Polymerization and self-assembly of thermally responsive in-chain functionalized double-hydrophilic macromonomers

Double-hydrophilic in-chain functionalized macromonomers consisting of poly(N-isopropylacrylamide) (PNIPAM) and poly(ethylene oxide) were prepared by a multistep procedure including esterification of PNIPAM monoester of maleic acid with α-methoxy-ω-hydroxypolyoxyethylene or its amidation with α-methoxy-ω-aminopolyoxyethylene. The polymerization of the macromonomers was carried out in aqueous solutions. The temperature was the key parameter controlling the polymerization process that was performed in the organized domains formed by the macromonomers below and above the phase transition temperature (Ttr). Polymacromonomers with higher degrees of polymerization were prepared at temperatures just below the Ttr. Static light scattering measurements on dilute aqueous solutions of thermally-responsive macromonomers and their polymerization products demonstrated that they formed aggregates below the Ttr. Supramolecular structures with low density cores, formed by the polymacromonomers at room temperature, were imaged by SEM. Morphological tuning was achieved by varying both the composition of the copolymer and the concentration of the aqueous solution. The rheological behavior of the polymacromonomers in 25 wt % aqueous solution was compared to that of the respective macromonomers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4720-4732, 2007