Microwave-assisted polymerization has been utilized to synthesize amphiphilic poly(2-ethyl-2-oxazoline-block-2-"soy alkyl"-2-oxazoline) diblock copolymers (PEtOx-PSoyOx). The amphiphilic block copolymers have been used to prepare aqueous spherical micelles consisting of a PEtOx corona and a PSoyOx core, which have been further cross-linked by UV irradiation. The morphology of these cross-linked micelles has been shown to reversibly change from spheres to short rods referred to as rice grains whenever the micelles were transferred from water into acetone, a nonselective solvent for the constituent blocks. This morphological transition has been attributed to the swelling of the slightly cross-linked PSoyOx core.
Huang, H., Hoogenboom, R., Leenen, M. A. M., Guillet, P., Jonas, A. M., Schubert, U. S., & Gohy, J. M. W. (2006). Solvent-induced morphological transition in core-cross-linked block copolymer micelles. Journal of the American Chemical Society, 128(11), 3784-3788. https://doi.org/10.1021/ja057762k