Pluronic copolymers

Rill, RL Liu, Y Van Winkle, DH Locke, BR, Pluronic Copolymer Liquid Crystals Unique, Replaceable Media for Capillary Gel Electrophoresis, Journal of Chromatography A817, 287, 1998. 

PEO-based copolymers have received much attention. In this respect, PEO-PPO and PEO-PPO-PEO Pluronic copolymers were investigated in organic solvents such as formamides, as illustrated by the works of Lindmann and coworkers and Alexandridis et al. [92-94], However, the formation of reverse micelles in organic solvents from PEO-based block copolymers has been shown to be a complex phenomenon due to the ability of PEO to crystallize. 

Face-centred cubic (FCC) structures have also been observed in Pluronic copolymers, using SAXS (Berret et al. 1996). In an aqueous poly(oxyethylene)-poly(oxybutylene) (PEO-PBO) diblock solution, both BCC and FCC phases... 

Fig. 4.1 Top schematic illustration of micellar phases formed by the Pluronic copolymer P85 (PE 026PP0i9 PEO,6) with increasing temperature. Bottom small-angle neutron scattering patterns from sheared solutions in D20 of this copolymer (25wt%). The three columns (left-right) correspond to a liquid spherical micelle phase at 25 °C, a cubic phase of spherical micelles at 27 °C and a hexagonal phase of rod-like micelles at 68 °C (Mortensen 1993a).

Similarly, Cherukuri et al. used the near-IR fluorescence of individualized semiconducting SWNTs to study their blood elimination kinetics and biodistribution in rabbits.127 The pluronic copolymer-coated SWNTs were intravenously administered into rabbits at a dose of 20 pg S WNT per kilogram of body mass. The pluronic coating was found to be displaced by blood protein within seconds, as indicated by changes in the near-IR emission spectra. The nanotube concentration in the blood semm decreased exponentially with a half-life of 1 h, and no adverse effects were observed in terms of the rabbit behavior and the pathological examination. At 24 h post administration, significant concentrations of nanotubes were found only in the liver.127... 

Pluronic copolymers with molecular weight of 11,500 have been used as a viscosity modifier and form a clear gel at 20 to 25% w/w in water. A solution of Pluronic undergoes a thermal gelation process in which a mixture of the polymer and water forms a clear solution at low temperature and then becomes a gel when raised to room temperature (above 21°C). A blend of Pluronic and lecithin is sold as Organogel for topical gel formulations. 

The inclusion complex formation between PEO blocks of the Pluronic copolymers and a-CD in the hydrogels was confirmed with wide-angle X-ray diffraction studies of the hydrogels [68], The effect of a-CD to aid the gelation of... 

Fig. 9 Proposed structure of the supramolecular hydrogel formed between a-CD and Pluronic copolymer in the presence of well-dispersed single-walled carbon nanotubes (SWNTs) [80]...

Emulsions are one of the most widely studied colloidal dispersion systems for the delivery of drugs (205,206). The oil-in-water emulsion is made of oil dispersed in an aqueous phase with a suitable emulsifier such as phospholipids and non-ionic or ionic surfactants. Castor oil or soybean oil is predominantly used as the core oil phase. Non-ionic surfactants such as Tween, Span, Brij, and pluronic copolymers are used as co-emulsifiers. The ionic co-emul-... 

Stable aqueous emulsions of poly(2-ethylhexyl acrylate) (PEHA) were also produced by RESAS from CO2 (68). In this case, a polymer suspension in CO2 was expanded instead of a dissolved solute. A C02-philic surfactant, Monasil PCA (PDMS-g-pyrrolidonecarboxylic acid), was utilized in dispersion polymerization to form a stable polymer suspension at 65°C and 345 bar. A hydrophilic surfactant, (e.g., SAM 185, Pluronic L61, or Pluronic L62), that is soluble in CO2 and CO2/2-EHA monomer mixtures as well as water was added to CO2 to stabilize the suspension after it had been rapidly expanded through a capillary into aqueous solution. The resulting aqueous emulsion with up to 15.6 wt % polymer content was stable for weeks with an average particle size of 2 to 3 pm. Another approach is to introduce the hydrophilic surfactant in the aqueous phase in addition to the surfactant in the CO2 phase. This approach is more general, since many hydrophilic surfactants are not soluble in CO2. During expansion of the suspension into an aqueous solution, the hydrophilic surfactant—for example, triblock Pluronic copolymers—dilfuses to the particle surface to provide stabilization. The resulting aqueous latexes were stable for 100 days for a polymer content reaching 12.7 wt %. 

J. Lee, P.A. Martic, and J.S. Tan. Protein adsorption on Pluronic copolymer-coated polystyrene particles. J. Colloid Interface ScL 131 252-266 (1989). 

In Pluronic copolymers, the number of ethylene oxide units is referred as 2a, e.g. L31 contains 8 ethylene oxide units. 

A triblock copolymer, Pluronic F-68, (polyethylene oxide-polypropylene oxide- polyethylene oxide triblock copolymer), a synthetic surfactant [74] was adsorbed to hydrophobic substrata such as PDMS to form low-density polymer brush-coatings [86]. The PEO-PPO-PEO triblock copolymers in many ways exhibit a similar behavior as low molecular weight non-ionic surfactants. The tendency of these amphiphilic polymers to self-assemble in aqueous systems and at interfaces has led to widespread applications for the stabilization of macromolecular colloidal suspensions and for the manipulation of surface properties [92]. Anti-fouling properties of Pluronic copolymers result from the fact that the Pluronic copolymers PPO domain, which... 

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