Micelle forming block copolymers

Topp MDC, Dijkstra PJ, Talsma H, Feijen J. Thermosensitive micelle-forming block copolymers of poly(ethylene glycol) and poly(iV-isopropylacrylamide). Macromolecules 1997 30 8518-8520. 

Scheme 7 Immobilization of RuCl2(CH-2,4,5-(OMe)3-C6H2)(l,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) on a micelle-forming block-copolymer...

Fig. 7 Chemical structures of micelle-forming block copolymers used in drug delivery.

Micelle-forming block copolymers were introduced by Yokoyama and coUeagues. " Conjugates of adriamycin with poly (ethylene glycol)-poly(aspartamide) block copolymers tend to form micelles (Fig. 34.7). It was demonstrated that these systems have a very high in vivo antitumour activity. 

Pratten MK, Lloyd JB, Horpel G, Ringsdorf H. Micelle-forming block copolymers Pinocytosis by macrophages and interaction with model membranes. Makromol Chem 1985 186 725-733. 

SVE Svensson, M., Linse, P., and Tjemeld, F., Phase behavior in aqueous two-phase systems containing micelle-forming block copolymers. Macromolecules, 28, 3597, 1995. 

Fig. 30 Types of nanocarriers for drug delivery, (a) Polymeric nanoparticles polymeric nanoparticles in which drugs are conjugated to or encapsulated in polymers, (b) Polymeric micelles amphiphilic block copolymers that form nanosized core-shell structures in aqueous solution. The hydrophobic core region serves as a reservoir for hydrophobic drugs, whereas hydrophilic shell region stabilizes the hydrophobic core and renders the polymer water-soluble.

The use of block copolymers to form a variety of different nanosized periodic patterns continues to be an active area of research. Whether in bulk, thin film, or solution micelle states, block copolymers present seemingly unlimited opportunities for fabricating and patterning nanostructures. The wealth of microstructures and the tunability of structural dimensions make them a favorable choice for scientists in a variety of research fields. As reviewed here, they can function as nano devices themselves, or act as templates or scaffolds for the fabrication of functional nanopatterns composed of almost all types of materials. However, there are still two obvious areas which require more work control of the long-range 3D nanostructure via more user-friendly processes and the identification of new materials with different functional properties. 

Manners, Winnick, and their collaborators22 have studied the self-assembly into cylindrical micelles of block copolymers formed from poly(ferrocenylsilanes) (R/R = Me/Me) and poly(dimethylsiloxane). By ensuring that the poly(dimethylsiloxane)... 

Fig. 1 Important parameters in the micellization of block copolymers. A is the insoluble block forming the micellar core, B is the soluble block forming the micellar shell or corona. Symbols are explained in the text...

Spherical micelles are not the only association structure that is formed by polyelectrolyte block copolymers. With increasing hydrophobic block length there is a tendency to form block copolymer vesicles. A vesicle formed by PB-P2VP.HC1 is shown in the cryo-TEM image in Fig. 14a. The bilayer structure is clearly resolved which shows that block copolymer vesicles are structurally very similar to lipid vesicles. Vesicles can be also imaged by AFM (Fig. 14b) where they exhibit a characteristic outer rim because the interior solution of the vesicle has evaporated during sample preparation leaving a shape that resembles that of an empty football. Vesicles typically have diameters of 100-300 nm and a bilayer thickness of 10-20 nm. 

Polymer micelle Amphiphilic block copolymers that form nanosized core—shell structure in aqueous solution. 

---