Micelles amphiphilic copolymers

Meijer et al. [135] further studied aggregation phenomena of amphiphilic copolymers obtained by modifying the termini of the dendrimer units of the above series with carboxylic acid groups (49). TEM experiments indicated that all block copolymers formed large aggregates except third generation copolymer which formed worm-like micelles. 

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.

Micelles from Amphiphilic Copolymers in Organic Solvents. 85... 

PEO chains have been grafted to this backbone, leading to an amphiphilic copolymer. Aqueous micelles have been then prepared from these copolymers [332]. 

Polymeric micelle formation occurs as a result of two forces. One is an attractive force that leads to the association of molecules while the other one, is a repulsive force, preventing unlimited growth of the micelles to a distinct macroscopic phase (Price, 1983 AstaLeva et al., 1993 Jones and Leroux, 1999). Amphiphilic copolymers form micellar structures through self-association of the insoluble segments when placed in a solvent that is selective for the other monomer (Kataoka et al., 1993 Jones and Leroux, 1999). The process of micellization for amphiphilic copolymers is similar to the process described for conventional hydrocarbon chain-based surfactants as described in the Lrst part of this chapter. 

Gitsov. L Lambrych. K.R. Remnant. V.A. Pracitto. R. Micelles with highly branched nanoporous interior Solution properties and binding capabilities of amphiphilic copolymers with linear dendritic architecture. J. Polym. Sci., A, Polym. Chem. 2000. 38, 2711-2727. 

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

Another property of polymers in the solubilised state that may be interesting for pharmaceutical formulations is a property specific to amphiphilic copolymers (see Section 4.1.1). Such copolymers can be used to formulate stable dispersions and emulsions. In general, they are highly efficient surfactants. Their critical concentration for micelle formation (CMC) is much lower, e.g. about 0.005 wt% in water, than the CMC of low-molecular-weight surfactants, e.g. 0.2 wt% for sodium dodecylsulphate. 

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