Block copolymer micelles synthesis

Loginova, T.P. etal. (2004) Molybdenum sulfide nanoparticles in block copolymer micelles synthesis andtribiological properties. Chemistry of Materials, 16,2369-2378. 

Zhang, Q., Ko, N.R., Oh, J.K. Recent advances in stimuh-responsive degradable block copolymer micelles synthesis and controlled drug delivery applications. Chem. Conunun. 48(61), 7542-7552 (2012)... 

Chastek TQ, lida K, Amis EJ, Fasolka MJ, Beers KL (2008) A microfluidic platform for integrated synthesis and dynamic light scattering measurement of block copolymer micelles. Lab Chip 8 950... 

The properties of polyelectrolyte block copolymer micelles have been investigated in detail in recent years. Due to the synthesis of well-defined polyelectrolyte block copolymers and the use of a variety of different experimental techniques the knowledge about polyelectrolyte block copolymer micelles and vesicles has well advanced. 

In addition to chemical methods variety of physical methods has been employed for the synthesis of AuNPs. UV irradiation is used to improve the quality of the AuNPs when it is used in synergy with micelles or seeds [32,33], Near-IR laser irradiation provokes an enormous size growth of thiol-stabilized AuNPs [34], The presence of an ultrasonic field (200 kHz) allowed the control of the rate of AuC14" reduction in an aqueous solution containing only a small amount of 2-propanol and the sizes of the formed AuNPs are controlled by varying the parameters such as the temperature of the solution, the intensity of the ultrasound, and the positioning of the reactor [35,36], Sonochemistry was also used for the synthesis of AuNPs within the pores of silica and for the synthesis of Au/Pd bimetallic particles [37,38], Radiolysis has been used to control the size of AuNPs [39], Laser photolysis has been used to form AuNPs in block copolymer micelles. Laser ablation is another technique of AuNP synthesis that has been used under various conditions whereby size control can be induced by the laser [40,41],... 

Well-characterized systems. This depends on the appropriate chemistry and subsequent characterization (typical issues here are the polydispersity, control of grafting density, reproducibility of procedure to obtain identical particles). One frequent problem here is that the price one pays for such systems is tlie availability of small amounts (sometimes only fractions of 1 g) of material. For example, multiarm star polymers are in many ways unique, clean, soft colloids [ 19,23], but their nontrivial synthesis makes them not readily available. On the other hand, recent developments witli block copolymer micelles from anionically synthesized polymers [54-58] and arborescent graft copolymer synthesis [40] appear to have adequately addressed this issue for making available different alternative star-like systems. 

Multiarm star polymers have recently emerged as ideal model polymer-colloids, with properties interpolating between those of polymers and hard spheres [62-64]. They are representatives of a large class of soft colloids encompassing grafted particles and block copolymer micelles. Star polymers consist of f polymer chains attached to a solid core, which plays the role of a topological constraint (Fig. Ic). When fire functionality f is large, stars are virtually spherical objects, and for f = oo the hard sphere limit is recovered. A considerable literature describes the synthesis, structure, and dynamics of star polymers both in melt and in solution (for a review see [2]). 

FIGURE 54.9 Synthesis of core cross-linked block copolymer micelles. (From J. Mater. Chem., 21(34), Kim, Y., Ponrgholami, M.H., Morris, D.L., and Stenzel, M.H., Triggering the fast release of drugs from cross-linked micelles in an acidic environment, 12777-12783. Copyright 2011. Reproduced by permission of The Royal Society of Chemistry.)... 

Matsumoto K, Matsuoka H (2005) Synthesis of core-crosslinked carbosilane block copolymer micelles and their thermal transformation to silicon-based ceramics nanoparticles. J Polym Sci A Polym Chem 43(17) 3778-3787... 

Antonietti M, Wenz E, Bronstein LM, Seregina MS (1995) Synthesis and characterization of noble metal colloids in block copolymer micelles. Adv Mater 7 1000-1005... 

Since synthetic copolymers seldom exhibit intrinsic fluorescence, either covalently bound fluorescent labels or non-covalently bound fluorescent probes are necessary for the vast majority of fluorescence studies of block copolymer micelles. The former are mostly attached during the synthesis of the copolymer [18]. This could be done conveniently by using a fluorescent initiator and/or fluorescent terminating agent. In such cases, the labels are located at the ends of the blocks or in between of them. Fluorescent probes can be used for studies of amphiphilic block copolymer micelles in aqueous solutions where strong hydrophobic effect allows for binding of the probe either in the micellar core (hydrophobic probes) [19] or in the iruier part of the shell close to the core/shell interface (amphiphilic probes) [20]. The latter, developed mainly for membrane studies, are derivatives of... 

Figure 16.11 TEM image in dark-field mode for shell-crosslinked cylinders of PFS53- -Pl32o block copolymers encapsulated with Ag nanoparticles. (Reprinted with permission from H. Wang, X. Wang, M.A. Winnik and I. Manners, Redox-mediated synthesis and encapsulation of inorganic nanoparticles in shell-cross-linked cylindrical polyferrocenylsilane block copolymer micelles, Journal of the American Chemical Society, 130, 12921, 2008. 2008 American Chemical Society.)...

More specifically, the synthesis of micelles as a scaffold for the formation of metal particles has been achieved (Loginova et al, 2004). This has been demonstrated very effectively by the group of Bronstein, who has utilized polystyrene as a reactive polymer to functionalize with molybdenum hexacarbonyl using UV radiation followed by reaction with H2S to afford MoS encapsulated micelles. In related work Chu has reported the use of block copolymer micelles as template s for the formation of hollow molybdenum spheres whose diameter is equivalent to the size of the micellar cores (about 5 nm) (Lui et al, 2000). More recently Xie and coworkers have used micelle-assisted fabrication of necklace-shaped molybdenum disulfide nanospheres (Xiong et al, 2003). In this work, the authors used the aggregation-driven transformation of surfactants at low temperatures to form a necklace-shaped assembly of amorphous M0S3 nanospheres. 

Diagram of synthesis procedures for modification of block copolymer micellar thin films by Incorporation of homopolymer (PS) into block copolymer micelles (PS-fr-PAA). 

Wang H, Wang X, Winnik MA, Manners I (2008) Redox-mediated synthesis and taicapsu-lation of inorganic nanoparticles in shell-cross-linked cylindrical polyforocenylsUane block copolymer micelles. J Am Chem Soc 130 12921-12930... 

The synthesis of the catalysts was based on the formation of metal compound NPs or metal NPs after reduction of metal corrqrounds in the cores of amphiphilic block copolymer micelles or in the pores of HPS [13-17]. 

The synthesis of these catalytic systems is based on incorporation of metal compoimds into the micelle core of amphiphilic block copolymer micelles followed by reduction with a formation of NPs. The core block contains functional groups which coordinate with metal compoimds and the core serves as a nanoreactor for NP formation, while the corona block provides solubihty in a selective solvent. 

This multitude of properties the polymer must possess dictate that better polymer performance will be obtained from materials with complicated structures. Such polymers are complex polymers l) random copolymers, 2) block copolymers, 3) graft copolymers, 4) micellizing copolymers, and 5) network copolymers. There has been a dramatic increase in the past decade in the number and complexity of these copolymers and a sizable number of these new products have been made from natural products. The synthesis, analysis, and testing of lignin and starch, natural product copolymers, with particular emphasis on graft copolymers designed for enhanced oil recovery, will be presented. 

SANS study of the mechanisms and kinetics of the synthesis of mesoporous materials from micelles of tri-block copolymers... 

Figure 2 Evolution of the neutron scattering intensities with time. Only spherical micelles of P123 block copolymer are present in the synthesis mixture within the first few minutes of the reaction (300 s), during the hydrolysis of the silica precursor. Then, hybrid organic-inorganic cylindrical micelles are detected (300-1400 s). The SBA-15 hexagonal phase is formed when the precipitation occurs, after 1400 s.

Here, we focus on one class ofblock copolymers synthesized by this method polystyrene-6-poly(vinylperfluorooctanic acid ester) block copolymers (Figure 10.33). After describing the synthesis and characterization, we will treat some properties and the potential applications of this new class ofblock copolymers. The amphiphilicity of the polymers is visualized by the ability to form micelles in diverse solvents that are characterized by dynamic light scattering (DLS). Then the use of these macromolecules for dispersion polymerization in very unpolar media is demonstrated by the polymerization of styrene in 1,1,2-trichlorotrifluoroethane (Freon 113). 

In a very recent set of papers [48,54,59,60,131,132,324-328], the synthesis and characterization of metallosupramolecular amphiphilic block copolymers containing a hydrophilic PEO block linked to a hydrophobic PS or PEB block through a fozs-2,2/ 6/,2/terpyridine-ruthenium(II) complex have been described. These copolymers form the so-called metallosupramolecular micelles . 

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