PEO molecules

Fig. 18 Phase space of PI-fc-PS-fc-PEO in vicinity of ODT. Filled and open circles-. ordered and disordered states, respectively, within experimental temperature range 100 < T/° C< 225. Outlined areas compositions with two- and three-domain lamellae (identified by sketches) shaded regions three network phases, core-shell double gyroid (Q230), orthorhombic (O70), and alternating gyroid (Q214). Overlap of latter two phase boundaries indicates high- and low-temperature occurrence, respectively, of each phase. Dashed line condition tfin = 0peo associated with symmetric PI-fc-PS-fc-PEO molecules. From [75]. Copyright 2004 American Chemical Society...

This result supports the micellar polymerization mechanism, i.e., the stronger hydrophobic intermolecular interactions between PEO molecules favors the... 

Diacyllipid-polyethyleneoxide conjugates have been introduced into the controlled drug delivery area as polymeric surface modiLers for liposomes (Klibanov et al., 1990). Being incorporated into the liposome membrane by insertion of their lipidic anchor into the bilayer, such molecules can ster-ically stabilize the liposome against interaction with certain plasma proteins in the blood that results in signiLcant prolongation of the vesicle circulation time. The diacyllipid-PEO molecule itself represents a characteristic amphiphilic polymer with a bulky hydrophilic (PEO) portion and a very short but extremely hydrophobic diacyllipid part. Typically, for other PEO-containing amphiphilic block... 

Wu et al. [161] studied the surface properties of PS and PMMA microspheres stabilized by PEO macromonomer, 26 (m=l) and 27b using dynamic light scattering and claimed that for PMMA microspheres the surface area occupied by a PEO molecule is nearly twice as large as that for PS microspheres, assuming that... 

The PEO solution is showing elastic properties. As we pour the solution, we are applying a shear force that tends to line up the very long PEO molecules. When this force is removed e.g., when the strand is cut), the molecules recoil to a lower energy state random coils), and in so doing cause the fluid above the cut to flow up. 

The polymer most commonly used to prepare brushes is poly (ethylene oxide) (PEO), which is alternatively called poly (ethylene glycol)(PEG). This is primarily because in an aqueous environment PEO molecules are highly mobile22 and strongly hydrated, attaining large exclusion volumes.23 Furthermore, PEO is biocompatible.24 Sometimes the role of polysaccharides to prevent bioadhesion is reported.25... 

It is well known that the presence of an excess of nonadsorbed polymer can result in flocculation of colloidal particles by the so-called depletion flocculation mechanism [13], In the clay-PEO system, the excess PEO molecules in the supernatant fluid would exert an osmotic pressure on the gel, and the effect should be similar to that of applying an external pressure to the gel indeed, because the... 

The main aim was to determine the distribution of PEO molecules between the gel and the supernatant fluid at r = 0.1, c = 0.1 M, T = 5°C for M = 18,000 (bridging) and polymer volume fractions in the range between v = 0 and v = 0.12. The corresponding neutron diffraction traces are shown in Figure 12.6a. In comparing these structural analyses with an independent analysis of the concentration of the PEO in the supernatant fluid, we established the following protocol in preparing the samples. 

Wu et al. [ 176] studied the surface properties of PS and PMMA microspheres stabilized by the PEO macromonomer 7 (m=l) using dynamic light scattering, and claimed that for PMMA microspheres the surface area occupied by a PEO molecule is nearly twice as large as that for PS microspheres, assuming that 100% macromonomer is copolymerized to attach to the latex surface. However, this is not the case for styrene copolymerization with PEO macromonomers in which only 10% PEO macromonomer was copolymerized [131]. In contrast, it was confirmed that 100% of PEO macromonomers were copolymerized for the MM A and BMA dispersion copolymerization [132, 133]. 

The corresponding AG(r) is shown in figure 2. A clear peak is observed at 1.1 A which corresponds to the characteristic C-H bond distance and coordination number in the polymer. It is clear that there is no strong structure at larger distances in the first order difference. This is largely due to the fact that the polymeric hydrogen is not at any particular centre of symmetry in relation to the hydrating water. However it is possible to reveal more of the hydration structure after the (known) intermolecular structure of the PEO molecule is subtracted firom the difference function. A detailed analysis of the result after this subtraction. 

Furthermore, it is also noted that the interlayer distance of the PCN is related to the intrinsic polymer structure, such that the PEO molecule exhibits a straight chain structure and has high backbone flexibility because of the backbone oxygen atom. Also, the minimum thickness required to accommodate this polymer is much smaller than the minimum layerthickness required for accommodating bulky PMMA molecules. 

Fig. 6 Representation of the amphiphUicity-driven self-assembly of Au-(PS-PEO)n nanoparticles (for simplicity reasons only six PS-PEO molecules are shown). This figure is a reproduction of Fig. lA from [39]...

As is seen, the change in the size of macromolecules at the cost of electrostatic tension affects the efficiency of turbulent friction reduction in a linear way, whereas the variation at the cost of molecular-mass increasing for neutral PEO molecules affects the efficiency in a more complicated way. 

The relative viscosity of the polyethylene oxide-surfactant solution, Tirel =n(PEO + surfactant)/(PEO), is plotted in Figure 2 as a function of the surfactant concentration for different surfactants. For anionic SDS, Heel remains invariant at 1 up to a concentration of 4 x 10 M, indicating absence of any association. Beyond 4 x 10 M SDS, the relative viscosity shows a large increase up to about 2.6 x 10 M SDS. This can be attributed to the association of SDS micelles with the PEO segments and the resulting expansion of the PEO molecules. Beyond 2.6 X 10 M SDS, a reduction in the relative viscosity is observed. This is because, when saturation binding of SDS to PEO is reached (say at 2.6... 

The plot of the reduced osmotic pressure versus the base molar fraction for the different temperatures (fig. 2) does not show a constant ordinate section. This indicates, that PEO molecules tend to associate with increasing temperature in aqueous solution. As the system has a closed miscibility gap C7] for temperatures well above 373 K, we expect the thermodynamic factor p = xVq (dn/dx )j p to tend to zero values... 

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