PEO-fc-PPO

Poly( ethylene oxide)-block-poly (propylene oxide)-hZock-poly(ethylene oxide)-g-poly(acrylic acid) (PEO-fc-PPO-fc-PEO-g-PAA, Pluronic-PAA) graft copolymers were synthesized by free radical grafting copolymerization of acrylic acid monomers onto PEO-h-PPO-h-PEO (Pluronic F127) and the aqueous solution properties were characterized by Bromberg [133, 134]. Chiu et al. [135] reported on the micellization of (non-ionic) poly(stearyl methacrylate)-gra/f-poly(ethylene glycol) graft copolymers. 

FIGURE 54.24 Illustration of preparation for microgels of PEO-fc-PPO-fc-PEO via inverse emulsion polymerization. (Reprinted with permission from Langmuir, 21(6), Missirlis, D., Tirelli, N., and Hubbell, J.A., Amphiphilic hydrogel nanoparticles. Preparation, characterization, and preliminary assessment as new colloidal drug carriers, 2605. Copyright 2005 American Chemical Society.)... 

FIGURE 6.1 Formation and architecture of block copolymer micelles, which spontaneously form by self-assembly in water. The characteristic features are a pronounced core-shell architecture, which can be controlled by the individual polymer blocks. Typical examples for block copolymers are PEO-fc-PPO, PEO- -PCL, and PEO-fc-PAsp. Source Kataoka et al. [1], figure 1. Reproduced with permission of Elsevier. (See insert for color representation of the figure.)... 

Another promising method is 2D-LC, a combination of adequately selected two different LC separation conditions. If the separation condition of one dimension separates one block in the IC mode while the other block does not show a strong interaction with the stationary phase, preferably weak enough to elute in the SEC mode (like simultaneous SEC/IC separation condition for mixtures), the interacting block can be separated by IC mode nearly independent of the non-interacting block length and vice versa. Employing the 2D-LC method, Murphy et al. and Jan-dera et al. separated individual blocks of alcohol ethoxylate and PEO-fc-PPO, respectively (Fig. 20) [137-139]. Due to the amphiphilic nature of the block copolymer, the combination of NPLC and RPLC worked well. 

The net effect of adsorbing either PEO-fc-PPO-fc-PEO or PLL-g-PEG onto hydrophobic surfaces is to cover the surface with hydrophilic PEO (or PEG) chains. With respect to aqueous lubrication of the thermoplastics in this work, this PEO (or PEG) layer is expected to make it feasible to form aqueous boimdary lubricant films due to improved affinity with water, as will be shown in the following section. 

Figure 5. Comparison of the coefficients of friction ( x) values for the self-mated sliding of the thermoplastics, polypropylene (PP), polyamide-6,6 (PA-6,6) and polyethylene (PE), lubricated by aqueous lubricants containing sodium dodecylsulphate (SDS), poly(ethylene oxide)- >tocA -poly(propylene oxide)-f>tocA -poly(ethylene oxide) (PEO-fc-PPO- >-PEO) and poly(L-lysine)-gra/t-poly(ethylene glycol) (PLL- -PEG) (load, ION diameter of the pin, 6 mm sliding speed, 5.1 mms number of rotations, 1000).

Mean-field lattice theory proved to be capable of predicting the phase behaviour of the ternary block copolymer polyethylene-fc-poly(propylene oxidc)-b-poly(ethylene oxide), PE-fc-PPO-fc-PEO in the selective solvent water [164]. The ethylene block is known to be highly hydrophobic, and its hydrophobicity does not depend strongly on temperature. The difference in hydrophobicity between PPO and PEO, on the other hand, is moderate... 

Then, the solution containing lubricant additives was injected into the flow cell. It is emphasised that the change in refractive index at this stage reflects the adsorption of additives, yet includes the contribution from the refractive index change of bulk solution itself as well. Tbe adsorbed mass was thus measmed only after the flow cell was rinsed with buffer solution. The refractive index increment (dn/dc) values of 0.151 and 0.169cm g were used for PEO-b-PPO-fc-PEO and PLL-g-PEG, respectively. 

Amphiphilic block copolymers in selective solvents undergo self-assembly into various nanosized morphologies [2,3]. Typical aggregates formed by the block copolymers are polymeric micelles with spherical shapes consisting of a core and a coronal shell. These spherical polymeric micelles are several tens of nanometers across with a narrow size distribution, and they are characterized by their unique core-shell structure, in which a core composed of insoluble blocks is surrounded by a palisade of soluble (hydrophihc) blocks. So far, polymeric micelles intended for biomedical use have been prepared from a variety of amphiphilic block copolymers including PEO-fc-PBLA [51-56], poly(ethylene oxide)-fc-poly(propylene oxide)-fc-poly(ethylene oxide) (PEO-fo-PPO-fo-PEO) (Pluronic) [9], PEO-fo-phosphatidylethanolamine (PEO-fo-PE) [12,13], PEO-fo-PDLLA [40-43], PEO-fc-poly(e-caprolactone) (PEO-fc-PCL) [11], and PEO-fo-poly(lactide-co-glycolic acid) (PEO-fc-PLGA) [57]. 

Although thermosensitive hydrogels formed from aqueous solution of poly(N-isopropylacrylamide) (PNIPAM), poly(2-ethoxyethyl vinyl ether)- -poly(2-methoxyethyl vinyl ether) (PEOVE-fc-PMOVE) and poly(ethylene oxide)-fc-poly(propylene oxide)-fc-poly(ethylene oxide) (PEO-f>-PPO-i -PEO)... 

Liaw J, Chang SF, Hsiao FC. In vivo gene delivery into ocular tissues by eye drops of polyCethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) polymeric micelles. Gene Ther 2001 8 999-1004. 

Scaffolds synthesized from HDI-derived segmented polyurethane elastomers have been reported to support bone healing in an ovine iliac crest defect model [46,47]. Chain extenders comprising 1,4-butanediol, 2-amino-l-butanol, 2-mercaptoethyl ether, and isosorbide diol [48-50] were investigated, as well as poly(ethylene oxide) (PEO), poly(ethylene-fc-propylene-Z -ethylene oxide) (PEO-PPO-PEO) block copolymers, and poly(caprolactone) macrodiols. Using a salt leaching/phase inversion technique, porous scaffolds with up to 90% porosity were fabricated from the HDI-derived... 

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