Formation of polyethylene glycol

The self-addition of ethylene oxide leads to the formation of polyethylene glycOl ... 

The critical diagram M vs retention time for a short RP-18 column of 60 mm length is shown in Fig. 7A. At acetonitrile concentrations > 47 vol.% in the solvent mixture, the retention time decreases as the molar mass of the PEO calibration sample increases retention corresponds to a size-exclusion mode. The reverse behaviour, i.e. the adsorption mode, is obtained at acetonitrile concentrations < 45 vol.%. The critical point of adsorption is operating at an eluent composition of acetonitrile-water 46 54 v/v, where separation is accomplished exclusively with respect to the functional endgroups- (see Fig. 7B). For the alkoxy-terminated PEOs, two distinctively different fractions are obtained, due to the formation of polyethylene glycol as an unwanted by-product. In the case... 

Other common poly glycol-based antifoams include certain derivatives of polyethylene glycol (PEG), which are condensation polymers of ethylene glycol. An example is polyethylene glycol-8 dioleate. Apart from its antifoam properties, PEG-8 dioleate is also used in cooling water inhibitor formulations as a surface cleaner, in the formation of a corrosion-inhibiting surface film. Additionally, it is employed as an oil-soluble emulsifier for other defoamer chemistries. 

The formation of peroxides and formaldehyde in the high-purity polyoxyethylene surfactants in toiletries has been shown to lead to contact dermatitis [31], Peroxides in hydrogenated castor oil can cause autoxidation of miconazole [32], Oxidative decomposition of the polyoxyethylene chains occurs at elevated temperature, leading to the formation of ethylene glycol, which may then be oxidized to formaldehyde. When polyethylene glycol and poloxamer were used to prepare solid dispersions of bendroflumethiazide, a potent, lipophilic diuretic drug, the drug reacted with the formaldehyde to produce hydroflumethiazide [33],... 

A further example of bisazolidization is the formation of a diamide from a succinic half-ester of polyethylene glycol) (MW 2000) via a bisimidazolide (A) or a bisben-zotriazolide (B) 11281... 

In a recent study, Jin and Kaplan (2003) demonstrate the formation of silk fibroin aggregates in the presence of polyethylene glycol, and present a step by step model for fiber formation based on the principle of micelle formation, and driven by dehydration as well as flow elongation. During this process, hydrophobic chains are exposed to the solvent, but because of the molecules high free energy, water solvation is unfavorable and phase separation followed by aggregation predominates. 

Otton, J. and Ratton, S., Investigation of the formation of polyethylene terephthalate) with model molecules. IV. Catalysis of the esterification of ethylene glycol with benzoic acid and of the condensation of ethylene glycol monobenzoate,J. Polym. Sci., Polym. Chem. Ed., 29, 377-391 (1991). 

Renwen, H., Feng, Y., Tinszheng, H. and Shiming, G The kinetics of formation of diethylene glycol in preparation of polyethylene terephthalate and its control in reactor design, Angew. Makromol. Chem., 119, 159-172 (1983). 

Hovenkamp, S. G. and Munting, J. P Formation of diethylene glycol as a side reaction during production of polyethylene terephthalate, J. Polym. Sci., Part A-1, 8, 679-682 (1970). 

Romson JL, Haack DW, Lucchesi BR (1980b) Electrical induction of coronary artery thrombosis in the ambulatory canine a model for in vivo evaluation of anti-thrombotic agents. Thromb Res 17 841-853 Ruebsamen K, Kirchengast M (1998) Thrombin inhibition and intracoronary thrombus formation effect of polyethylene glycol-coupled hirudin in the stenosed, locally injured canine coronary artery. Coron Artery Dis 9 35-42 Sullivan J, Hansen P, Rahko PS, Folts JD (1992) Continous measurement of left ventricular performance during and after maximal isometric deadlift exercise. Circulation 85 1406-1413... 

The application of cesium fluoride as base in the synthesis of crown compounds from phenols and the ditosylates of polyethylene glycols was first described by Reinhoudt [44]. This method uses the high basicity of weakly solvated ( naked ) fluoride anions under aprotic conditions and is based on the formation of very stable H—F bonds (approx. 569 kJ/mol, H—Cl approx. 432 kJ/mol for comparison) [8],... 

The sonication was carried out in a Bandelin Sonopuls HD 3200 system with 200 W input power and working frequency of 20 kHz, 50% amplitude. In the experiments, 2 g of cobalt carbonyl (5.8 mmol) were dissolved in 100 ml of the deionized water (sample 1) or in a water-alcohol (1 1 volume) mixture (sample 2) until the formation of colloidal solution. Then 0.5 g of polyethylene glycole was added to the mixture. The resulted solution was purged with argon for 10 min before the ultrasonication and also during the reaction. The high-intensity Ti horn with a diameter of 6 mm and tip surface area of 113 mm was used. The ultrasonication was carried out for 40 min. The resulted solutions were... 

The XRD patterns of samples 1 and 2 are similar (Fig. 1). The samples consist of polyethylene glycol, Co, and C03O4. The XRD pattern of sample 2 is noised and worse resolution than the pattern of sample 1. That can be related to the formation of an amorphous phase or small size of particles. 

In a dehydrated state, the frequency corresponding to the PO2 group asymmetric mode of vibration is 1237 run. Upon full hydration (18 to 20 water molecules per lipid) the frequency decreases to 1211 nm because of the formation of hydrogen bonds with the water molecules. When fully hydrated lipids are subjected to a hypertonic shock by the addition of polyethylene glycol (PEG), the frequency increases in 6 nm, indicating a small but significant water displacement from the phosphate regions. 

Two methods to prepare polyether-based podands are described here. The first is a direct modification of polyethylene glycols and comes originally from the work of Piepers and Kellogg [6], later modified by Hosseini [7]. A simple reaction between hexaethylene glycol and isonicotinyl chloride, as shown in Figure 1.2, results in the formation of podand 1 in good yield. When treated with silver salts... 

To determine trace components in arsenic trichloride the inlet portion of the column was filled with 15% of tricresyl phosphate on Chromosorb W [47]. In this portion arsenic trichloride was completely retained as a result of the formation of a stable complex with tricrysyl phosphate. The trace components were separated in the remainder (main portion) of the column packed with 10% of polyethylene glycol 400 (PEG-400). 

Wojtczak have found that the photosensitized degradation of polyethylene glycols decreases in the order triethylene glycol > polyethylene glycol 400 mol. wt. > polyethylene glycol 4000 mol. wt. Sastre and Gonzalez have shown that bromoalkanes are powerful sensitizers for the photo-oxidation of polystyrene, and Rabek and Ranby have found that polynuclear aromatics are photosensitizers for polybutadiene. Aromatic carbonyls have been shown to induce free-radical formation in cellulosic materials. 

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