| Multicompartment micelles, nanoscopic assemblies of amphiphile, with subdivided solvophobic cores surrounded by a solvophilic corona, is an exciting area of polymer science due to potential applications. This novel type of micelle can be obtained by self-assembly of mu-EOF miktoarm star terpolymers (PEE/E: poly(ethylethylene); PEO/O: poly(ethylene oxide); PFPO/F: poly(perfluoropropylene oxide)) in water. mu-EOF multicompartment micelles are capable of simultaneously storing two incompatible payloads in discrete PEE and PFPO core subdomains, desirable for advanced drug delivery.;Ideally, the sequential release of the encapsulated payloads could be achieved by the transition of E block from core to corona. By introducing tetrahydrofuran (THF) into aqueous dispersion, mu-EOF micelles evolve from multicompartment (PEE + PFPO) disk-like micelles to core-shell-corona (PFPO-PEE-PEO) worm-like and spherical micelles, and finally to mixed corona (PEE + PEO) elliptical oblate micelles with increasing THF content.;We have synthesized PDMA diblock copolymers (P/PEP: poly(ethylene propylene); DMA/PDMAEMA: poly[2-(dimethylamino)ethyl methacrylate]), where PDMAEMA is a weak polybase. As pH increases from 2.6 to 9.0, DMA switches from hydrophilic to mostly hydrophobic. Correspondingly, PDMA micelles transform from spherical to worm-like micelles.;However, other stimuli such as pH or temperature are more desirable to achieve the evolution from multicompartment micelles to mixed-corona micelles. Thus, we have designed and synthesized new mu-SODA miktoarm star terpolymers (PS/S: poly(styrene); PDMAEA/DA: poly[2-(dimethylamino)ethyl acrylate]), where PDMAEA is the poly(acrylate) version of PDMAEMA. mu-SODA micelles evolve from multicompartment (PS+PDMAEA) worm-like micelles to mixed-corona (PEO+PDMAEA) spherical micelles as pH decreases from 9.0 to 2.6. A similar evolution is also observed for linear OSDA and SODA terpolymers.;Finally, micelle morphological evolution upon photo-induced degradation has been studied using mu-[poly(ethylethylene)][poly(ethylene oxide)][poly( n-butyl acrylate)] (mu-EOBA) miktoarm star terpolymers that contain a photocleavable group at the junction. As most of poly(n-butyl acrylate) chains are photocleaved from the junction and undergo further photolysis, mu-EOBA micelles evolve from either a mixture of segmented wormlike and spherical micelles or irregular nanostructured bilayers to more regular disk-like micelles.;Overall, the above micelle-to-micelle morphological evolutions hold promise for the development of "smart" delivery capabilities. |
