Block copolymers micelle formation

Poly(styrene-ethylene oxide) block copolymer micelle formation in water a uorescence probe study. Macromolecule 4 1033-1040. 

Calderara F, Hruska Z, Hurtrez G, Lerch J-P, Nugay T, Riess G. Investigation of olystyrene-polyCethylene oxide)block copolymer micelle formation in organic and aqueous solutions by nonradiative energy transfer experiments. Macromolecules 1994 27 1210-1215. 

Wilhelm M, Zhao C-L, Wang Y, Xu R, Winnik R-A. Poly(styr-ene-ethylene oxide) block copolymer micelle formation in water A fluorescence probe study. Macromolecules 1991 24 1033-1040. 

Wilhelm M, Zhao CL, Wang YC, Xu RL, Winnik MA, Mura JL, Riess G, Croucher MD (1991) Polymer micelle formation. 3. Poly(styrene-ethylene oxide) block copolymer micelles formation in water—a fluorescence probe study. Macromolecules 24 1033-1040... 

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. 

Addition of a selective solvent to molecularly dissolved chains has been used by many research teams to prepare block copolymer micelles. The initial nonselective solvent can be further eliminated by evaporation or can be gradually replaced by the selective solvent via a dialysis process. The stepwise dialysis initially introduced by Tuzar and Kratochvil is now widely used for micelle preparation [6], especially for the formation of aqueous micelles [32],... 

Liu T, Liu LZ, Chu B (2000) Formation of amphiphilic block copolymer micelles in nonaqueous solution. In Alexandridis P, Lindman B (eds) Amphiphilic block copolymers self-assembly and applications. Elsevier, Amsterdam... 

Application of amphiphilic block copolymers for nanoparticle formation has been developed by several research groups. R. Schrock et al. prepared nanoparticles in segregated block copolymers in the sohd state [39] A. Eisenberg et al. used ionomer block copolymers and prepared semiconductor particles (PdS, CdS) [40] M. Moller et al. studied gold colloidals in thin films of block copolymers [41]. M. Antonietti et al. studied noble metal nanoparticle stabilized in block copolymer micelles for the purpose of catalysis [36]. Initial studies were focused on the use of poly(styrene)-folock-poly(4-vinylpyridine) (PS-b-P4VP) copolymers prepared by anionic polymerization and its application for noble metal colloid formation and stabilization in solvents such as toluene, THF or cyclohexane (Fig. 6.4) [42]. 

Computer simulations of a range of properties of block copolymer micelles have been performed by Mattice and co-workers.These simulations have been based on bead models for copolymer chains on a cubic lattice. Types of allowed moves for bead chains are illustrated in Fig. 3.27. The formation of micelles by diblock copolymers under weak segregation conditions was simulated with pairwise interactions between A and B beads and between the A bead and vacant sites occupied by solvent, S (Wang et al. 19936). This leads to the formation of micelles with a B core. The cmc was found to depend strongly on fVB and % = x.w = %AS. In the range 3 < (xlz)N < 6, where z is the lattice constant, the cmc was found to be exponentially dependent onIt was found than in the micelles the insoluble block is slightly collapsed, and that the soluble block becomes stretched as Na increases, with [Pg.178]

Hurterr, P. N., J. M. H. M. Scheutjens, T. A. Hatton, and T. Alan. 1993. Molecular modeling of micelle formation and solubilization in block copolymer micelles. 1. Aself-consistent mean- eld lattice theory. Macromolecule26 5592-5601. 

Fig. 12 AFM-images of polyelectrolyte block copolymer micelles (PEE-PSSH) at no added salt (a), 0.1 mol/1 (b) and 1 mol/1 (c). The formation of strings, loops and networks occurs with increasing salt concentration [45, 46]...

Figure 26 Formation of two-dimensional lattices of spherical particles like block copolymer micelles on a flat substrate [313]...

Selvan and coworkers167168 utilized a block copolymer micelle of polystyrene-block-poly(2-vinylpyridine) in toluene exposed to tetrachloroauric acid that was selectively adsorbed by the micelle structure. On exposure of this solution to pyrrole monomer, doped PPy was obtained concurrently with the formation of metallic gold nanoparticles. The product formed consisted of a monodispersed (7-9 nm) gold core surrounded by a PPy shell. Dendritic nanoaggregate structures were also reported... 

PS-b-P4VP-based Catalysts In the mid-1990s we developed nanoparticulate catalysts based on block copolymer micelles derived from the polystyrene-felocfe-poly-4-vinylpyridine (PS-b-P4VP) [11, 46]. In selective solvents (toluene and THE) these block copolymers form micelles with the P4VP cores, the latter serve as nanoreactors for metal nanopartide formation. The Pd nanopartides of 2.6 nm... 

Unlike PEO- -P2VP, the PEO-fe-PB block copolymer micelles in water are very dense, so they successfully fulfill two roles They serve as nanoreactors for Pd, Pt, and Rh nanoparlicle formation and as metal-particle-containing templates for mesoporous silica casting [41]. Figure 4.10 presents PEO- -PB micelles (M = 13,400 = 19,200) filled with Pd nanoparticles and meso-... 

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