Triblock copolymer Pluronic

Hadden, DA, Master of Science Thesis, Florida State University, Tallahassee, FL, 1999. Hadden, D Rill, RL McFadden, L Locke, BR, Oligonucleotide and Water Self-Diffusion in Pluronic Triblock Copolymer Gels and Solutions by Pulsed Field Gradient Nuclear Magnetic Resonance, Macromolecules 33, 4235, 2000. 

Apparent advantage of the prefabricated nanoparticles hes in the opportunity to use well-developed procedures to control particle size and particle size distribution and to characterize the particles by all possible means. Prefabricated particles can be introduced in the mesoporous materials in two ways. One avenue is direct incorporation of particles in sol-gel mixture as was recently reported in [60]. Here mesostructured nanoparticle-sihca monoliths have been synthesized by dispersing prefabricated Au or zeohte (sihcate) nanoparticles in sol-gel precursors containing SiCl4 and a Pluronic triblock copolymer template. To improve the compatibility of the Au nanoparticles with the poly(ethylene oxide) block, the nanoparticle surface was modified with a SiOj layer. Therefore, this technique requires good compatibihty of nanoparticles with the components of the sol-gel reaction, as it influences the distribution of nanoparticles through the material. Another hmitation of this method is encapsulation of particles within mesoporous material, but not necessary location in the pores. As was discussed above, this limitation is especially crucial for catalytic applications. 

In a detailed study of the adsorbed DHBCs chain conformation, Hamley et al. have presented experimental results on adsorbed Pluronic triblock copolymers onto both silica and mica substrates [106]. The experimental data were obtained for a wide range of bulk polymer concentrations, even below the critical micelle concentration. The results indicate that, depending on the hydrophilicity of the substrate, the copolymer chains are adsorbed in a completely different way. Moreover, it was concluded that the polymer concentration plays a significant role on the conformation of the adsorbed polymeric layer. 

This article aims to review the recent developments in the area of BCP-surfactant mixed systems in aqueous solution and is organized as follows For historic reasons and due to the high number of publications devoted to Pluronics, triblock copolymers will be discussed first, and their behavior in aqueous mixtures with different surfactants will be reviewed (Section 2). 

Amphiphilic Pluronic triblock copolymers of two blocks of poly-(ethylene oxide) (PEO) and poly(propylene oxide) in between have worth as both the surface modifier and pore former in the fabrication of membranes (77). The effect of Pluronics with different molecular architectures and contents as a pore forming additive for the fabrication of poly(ethersulfone) ultrafiltration hollow fibers has been investigated. 

Figure 9 shows that the maaolattices of interest in polymer systems do not have to be two-phase systems. Pluronic triblock copolymer gels are known to undergo a temperamre-dependent transition from a low viscous sol phase at low temperatures to a highly viscous gel phase formed by core-shell micelles with... 

Porous membranes have been prepared by leaching an additive from films and tubes of PCL (64,72). The procedure involves extrusion or casting blends of PCL and Pluronic F68, the latter being an FDA-approved oxyethylene-co-oxypropylene triblock copolymer. Treatment of the phase-separated blend with aqueous acetone or aqueous alcohols causes both swelling of the polymer and extraction of the Pluronic F68. The induced pore size and void volume may be controlled by the time, temperature, and solvent composition. 

Fig. 22 Images and data representing development and application of DLS on a chip a one iteration in the design of a microfluidic DLS fabricated from aluminum with the surface anodized black to reduce surface reflections b image of a microfluidic chip that integrates polymer synthesis with DLS. The machined channels have been covered by a Kapton sheet fixed with adhesive c data for temperature depended micelle formation of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (Pluronic P85) at 2% by volume in water. (Derived from [106] with permission)...

Self-consistent field theory (SCFT, see Sections 2.3.3 and 3.4,2) has recently been applied to the phase behaviour of ordered micellar solutions. Noolandi et al. (1996) compared continuum SCFT to the lattice version of this theory for triblock copolymers such as the Pluronics in aqueous solution. From a different viewpoint, this work represents an extension of the SCFT employed by Hong and Noolandi (1981, 1983) and Matsen and Schick (1994) for the phase behaviour of block copolymer melts to block copolymers in solution. The approximations introduced by the adoption of a lattice model are found to lead to some significant differences in the solution phase behaviour compared with the continuum theory, as illustrated by Fig. 4.44. For example, the continuum theory predicts ordered phases for Pluronic L64 (PE013PP03oPEO 3), whereas the lattice theory (neglecting polydispersity) predicts none. 

Of the triblock copolymers, the Pluronic series are the most popular. According to the product information by BASF, the nomenclature of Pluronic surfactants can be described based on the molecular weight ranges of the hydrophobe propylene oxide (PO) against the weight-percent of the hydrophile ethylene oxide (EO) present in each molecule. The letter-number combinations can be... 

Pluronic-g- polyethyleneimine (Pluronic-g-PEI) Graft-copolymer, branched PEI segment grafted with nonionic triblock copolymer In vitro and in vivo transfections and oligonucleotide delivery (Nguyen etal., 2000)... 

There is a vast body of diblock copolymer studies since block choice can be such that they resemble amphiphilic surfactants. For the sake of brevity, we will skip them. Instead, we present an interesting case of triblock copolymers of poly(ethylene oxide), PEO, and poly(propylene oxide), PPO, commonly known by one of its trade names, Pluronics [117]. They have been used as non-ionic surfactants for a variety of applications such as in emulsification and dispersion stabilization. In aqueous solutions, these copolymers form micelles, and there exists a well-defined critical micelle concentration that is experimentally accessible. Several groups have investigated colloidal suspensions of these polymers [118-122], The surface properties of the adsorbed monolayers of the copolymers have been reported with respect to their structures and static properties [123-126]. 

Li and Caldwell used S-FFF to determine the mass and surface concentration of absorbed PEO-PPO-PEO triblock copolymers (Pluronics) onto PS latex standards [185]. Fl-FFF was found to work equally well for this problem. As experimental absorption problems are widespread and extremely relevant, it is expected that FFF will play an important future role in such studies, as long as the mass of the absorbed layer is sufficiently high. 

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