Modification of polyethers

MODIFICATION OF POLYETHERS BY WATER SOLUTIONS OF ALKALIS WITH THE PURPOSE OF OBTAINING A ROUGH SURFACE... 

A. Ameri, M. Gholami, N. Nasseri, T. Matsuura, Modification of polyether sulfone (PES) hollow fiber membranes characteristics for more efficient water treatment process, Iran J Public Health, 33, 49-55. 2004. 

Propylene oxide has found use in the preparation of polyether polyols from recycled poly(ethylene terephthalate) (264), haUde removal from amine salts via halohydrin formation (265), preparation of flame retardants (266), alkoxylation of amines (267,268), modification of catalysts (269), and preparation of cellulose ethers (270,271). 

Chemical modification of monensin, polyether ionophoric antibiotic with bound tetrahydropyran, two tetrahydrofuran, and octahydrospiro-2,2 -furopyran fragments 97YZ583. 

The investigation of the chemical modification of dextran to determine the importance of various reaction parameters that may eventually allow the controlled synthesis of dextran-modified materials has began. The initial parameter chosen was reactant molar ratio, since this reaction variable has previously been found to greatly influence other interfacial condensations. Phase transfer catalysts, PTC s, have been successfully employed in the synthesis of various metal-containing polyethers and polyamines (for instance 26). Thus, the effect of various PTC s was also studied as a function of reactant molar ratio. 

CAPTOR A modification of the "Activated Sludge sewage treatment system, in which the micro-organisms are retained in a reticulated polyether foam. Invented in 1978 at UMIST, Manchester, and developed by Simon-Hardey, UK. 

Crown-ethers are macrocyclic polyethers capable of forming host-guest complexes, especially with inorganic and organic cations. Modification of the crown-ether by the introduction of four carboxylic groups makes it possible to use this class of compounds as chiral selectors in CE. ... 

In most cases, a suitable molecular modification of the catalyst structure is required to obtain the desired thermoresponsive properties. Polyether and in particular PEG substituents are receiving considerable interest in this field. The present study has addressed structure-activity relationships for well-defined low molecular weight model ligands in the rhodiiun-catalyzed hydroformylation of 1-octene as benchmark reaction. Figure 3 summarizes the observed trends. 

Recent work on the synthesis, structure and some properties of macromolecules bearing furan rings is discussed. Two basic sources of monomers are considered, viz. furfural for monomers apt to undergo chain polymerization and hydroxymethylfurfural for monomers suitable for step polymerization.Within the first context, free radical, catiomc and anionic systems are reviewed and the peculiarities arising from the presence of furan moieties in the monomer and/or the polymer examined in detail. As for the second context, the polymers considered are polyesters, polyethers, polyamides and polyurethanes. Finally, the chemical modification of aU these oligomers, polymers and copolymers is envisaged on the basis of the unique reactivity of the furan heterocycle. 

Several amine functionalized hyperbranched PGs have been reported as potential gene delivery systems after a proper surface group functionalization. In comparison to other dendritic structures, these scaffolds have the added advantage of being open, flexible, and possessing a polyether backbone which keeps the toxicity profile low. Different systems have been studied by post-modification of the hydroxyl groups... 

Sulfonation is very useful chemical modification of polymer, as it induces high polarity in the polymer changing its chemical as well as physical properties. Sulfonated polymers are also important precursors for ionomer formation [75]. There are reports of sulfonation of ethylene-propylene diene terpolymer (EPDM) [76, 77], polyarylene-ether-sulfone [78], polyaromatic ether ketone [79], polyether ether ketone (PEEK) [80], styrene-ethylene-butylene-styrene block copolymer, (SEBS) [81]. Poly [bis(3-methyl phenoxy) phosphozene] [82], Sulfonated polymers show a distinct peak at 1176 cm"1 due to stretching vibration of 0=S=0 in the -S03H group. Another peak appears at 881 cm 1 due to stretching vibration of S-OH bond. However, the position of different vibrational bands due to sulfonation depends on the nature of the cations as well as types of solvents [75, 76]. 

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... 

In 1968, Ontario Research Foundation developed a series of segmented polyether polyurethanes as polymer membrane materials for reverse cosmosis, ultrafiltration and hemodialysis. The elastomers of recent implant studies are polyurea-urethanes( .) with modification of the synthesis limited to only one variable— the chain length of the polyether component. 

In most of our studies, modification of the synthetic route was limited to only one variable, the chain length of the polyether component. The same molar ratio of polyether/chain extender disocyanate (MDI) and chain extender (diethlene glycol) were used. The molecular weight of the polyether component of J-20, J-9 and J-6 was 2,000, 1,000 and 600 respectively. A wide range of properties was obtained from this series of polyurethanes. Properties intermediate between J-20 and J-9 were also obtained by... 

Other modifications of vegetable oils in polymer chemistry include the introduction of alkenyl functions, the study of novel polyesters and polyethers and the synthesis of semi-interpenetrating networks based on castor oil (the triglyceride of ricinoleic acid) [42], and also the production of sebacic acid and 10-undecenoic acid from castor oil [44]. Additionally, the recent application of metathesis reactions to unsaturated fatty acids has opened a novel avenue of exploitation leading to a variety of interesting monomers and polymers, including aliphatic polyesters and polyamides previously derived from petrochemical sources [42, 45]. 

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