Copolymer micelles

Another example of OTHdC application is the study of the association/ dissociation of copolymer micelles. Using the light-scattering technique, the... 

Fig. 6. Possible structures of block copolymer micelles. Top Hairy micelle Bottom Crew-cut micelle...

Tamil S.S., Spatz, J.P., Klok H.A., and Martin M. Gold-polypyrrole core-shell particles in diblock copolymer micells, Aiiv. Mater., 10, 132, 1998. 

Kwon GS, Naito M, Kataoka K, Yokoyama M, Sakurai Y, Okano T (1994) Block copolymer micelles as vehicles for hydrophobic drugs. Colloids Surf B 2 429-434... 

Figure 23. Polymer A and polymer B form the diblock copolymer micelles where metal nanoparticles can be grown.

Nanometer size Pd colloids in block copolymer micelles of polystyrene polyvinylpyridine as catalysts have been used is a novel way by Klingelhofer for Heck reaction of C-C coupling of aryl halides with olefins. 

Figure 11.8 Formation of ordered nanoparticles of metal from diblock copolymer micelles, (a) Diblock copolymer (b) metal salt partition to centres of the polymer micelles (c) deposition of micelles at a surface (d) micelle removal and reduction of oxide to metal, (e) AFM image of carbon nanotubes and cobalt catalyst nanoparticles after growth (height scale, 5 nm scan size, lxl pm). [Part (e) reproduced from Ref. 47].

Adhikari A, Dey S, Das DK, Mandal U, Ghosh S, Bhattacharyya K (2008) Solvation dynamics in ionic liquid swollen P123 triblock copolymer micelle a femtosecond excitation wavelength dependence study. J Phys Chem B 112(20) 6350-6357... 

In this paper, we report about a recent in situ SANS study of the synthesis of the SBA-15 materials [5]. Our results demonstrate that SANS (using D20 instead of H20 as a solvent) is a powerful tool for the determination of size and shape of hybrid inorganic-organic micelles during the first synthesis step when the precursor species undergo hydrolysis and form an inorganic framework around the copolymer micelles. 

The SANS data reveal an induction period of 5 minutes after the TEOS addition, during which the copolymer micelles do not evolve (figure 2). This induction period corresponds to the hydrolysis of TEOS, as shown by a recent complementary in-situ Raman study [3,8],... 

Kakizawa Y, Kataoka K (2002) Block copolymer micelles for delivery of gene and related compounds. Adv Dmg Deliv Rev 54 203-222... 

Kang N, Perron ME, Prudhomme RE et al (2005) Stereocomplex block copolymer micelles core-shell nanostructures with enhanced stability. Nano Lett 5 315-319... 

Gaucher G, Dufresne MH, Sant VP et al (2005) Block copolymer micelles preparation, characterization and application in drug delivery. J Control Release 109 169-188... 

Kataoka K, Matsumoto T, Yokoyama M et al (2000) Doxorubicin-loaded poly(ethylene glycol)-poly(P-benzyl-L-aspartate) copolymer micelles their pharmaceutical characteristics and biological significance. J Control Release 64 143-153... 

Lee ES, Shin HJ, Na K et al (2003) Poly(L-histidine)-PEG block copolymer micelles and pH-induced destabilization. J Control Release 90 363-374... 

Colloidal catalysts in alkyne hydrogenation are widely used in conventional solvents, but their reactivity and high efficiency were very attractive for application in scC02. This method, which is based on colloidal catalyst dispersed in scC02, yields products of high purity at very high reactions rates. Bimetallic Pd/Au nanoparticles (Pd exclusively at the surface, while Au forms the cores) embedded in block copolymer micelles of polystyrene-block-poly-4-vinylpyridine... 

The micelle formation is not restricted to solvents for polystyrene but also occurs in very unpolar solvents, where the fluorinated block is expected to dissolve. Comparing the data, we have to consider that the micelle structure is inverted in these cases, i.e., the unpolar polystyrene chain in the core and the very unpolar fluorinated block forming the corona. The micelle size distribution is in the range we regard as typical for block copolymer micelles in the superstrong segregation limit.2,5,6 The size and polydispersity of some of these micelles, measured by DLS, are summarized in Table 10.3. 

Hydrodynamic diameters dh and corresponding Gaussian width c of block copolymer micelles in solvents of decreasing polarity. None means that no micelles could be detected by DLS. 

Abstract This review summarizes recent advances to date in the area of block copolymer micelles and also tries to highlight some new directions in that field. Generalities... 

From a morphological point of view, block copolymer micelles consist of a more or less swollen core resulting from the aggregation of the insoluble blocks surrounded by a corona formed by the soluble blocks, as decribed in Sect. 2.3. Experimental techniques that allow the visualization of the different compartments of block copolymer micelles will be presented in Sect. 2.4. Other techniques allowing micellar MW determination will also be briefly discussed. Micellar dynamics and locking of micellar structures by cross-linking will be commented on in Sects. 2.5 and 2.6, respectively. 

Selected examples of block copolymer micelles in both aqueous and organic media will then be presented in Sects. 3 and 4. Section 4.3 emphasizes stimulus-responsive micellar systems from double-hydrophilic block copolymers. Prediction of the dimensional characteristic features of block copolymer micelles and how it varies with the composition of the copolymers will be shortly outlined in Sect. 5, with a consideration of both the theoretical and experimental approaches. Tuning of micellar morphology and triggering transitions between different morphologies will then be discussed in Sect. 6. 

With the increasing number of publications on block copolymer micelles (a database literature search with these three associated keywords already gives more than 500 references), an exhaustive description of all previous works would not be possible in the framework of the present review. This contribution has rather as its purpose giving a general overview about block copolymer micelles for the nonspecialist and will therefore try to answer such practical questions as how does one prepare block copolymer micelles How does one characterize them What are the different types of structures that can be formed How can we predict them How does one tune the morphology of these micelles These basic questions and the corresponding answers will be illustrated by selected examples. Then, we will focus on the new directions that are currently implemented in this field. 

The research area of block copolymer micelles has been reviewed by other authors including Price [4], Piirma [5], Tuzar and Kratochvil [6], Riess and coworkers [7,8], Webber et al. [9], Alexandridis and Hatton [10], Nace [11], Hamley [2], Alexandridis and Iindman [12], and Xie and Xie [13]. A very complete review on block copolymer micelles was published recently by... 

Generalities about block copolymer micelles have been reviewed by Ham-ley [2] and Riess [14], based on previous works from the 1980s and 1990s. This topic will not be covered in detail, but the basic principle, as well as some important practical issues, will be reviewed. The essential experimental techniques used for block copolymer micelle characterization will also be outlined briefly. 

Although it strongly influences the micellar characteristic features, the method used for the preparation of block copolymer micelles has been very often poorly discussed in the literature. This crucial point was raised in the excellent review of Riess [14]. 

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