Grafting, anionic Polyethylene

A similar approach was used in grafting Cjq onto a pregenerated lithiated polyethylene surface [121]. A polyethylene film with terminal diphenylmethyl groups was deprotonated with BuLi to yield an anionic polyethylene surface that was treated with Cg0 and quenched with methanol. The incorporation at the polyethylene surface was determined by XPS, UV/Vis and fluorescence spectroscopy. This reaction also works for polyisopropene, polybutadiene [69], poly(vinylbenzyl chloride) or poly(N-vinylcarbazole) PVK [54] with BuLi or NaH as a base. Charge-transfer interactions in the soluble fullerene-PVK derivative between the positively charged carbazole and Cjq lead to an enhanced photoconductivity compared with PVK [54]. 

T.A. Sherazi, J.Y. Sohn, YM. Lee, and M.D. Guiver, Polyethylene-based radiation grafted anion-exchange membranes for alkaline fuel cells, Journal of Membrane Science, 441, 148-157, 2013. 

Several authors have discussed the ion exchange potentials and membrane properties of grafted cellulose [135,136]. Radiation grafting of anionic and cationic monomers to impart ion exchange properties to polymer films and other structures is rather promising. Thus, grafting of acrylamide and acrylic acid onto polyethylene, polyethylene/ethylene vinyl acetate copolymer as a blend [98], and waste rubber powder [137,138], allows... 

In a similar manner polyisoprene-polyethylene oxide block copolymers can prepared301. It is surprising that the poly(methyl methacrylate) anion can be successfully used for the polymerization of ethylene oxide without chain transfer302. Graft copolymers are also prepared by successive addition of ethylene oxide to the poly-... 

The lithiated polyethylene copolymer was then suspended in hexane or THF solvent. The graft-from reactions were carried out in slurry solution by reacting the lithiated polyethylene copolymer with anionic polymerizable monomers, such as styrene and p-methylstyrene. After certain reaction time, 10 ml of isopropanol was added to terminate the graft-from reaction. The precipitated polymer was filtered and then subjected to fractionation. Good solvents for backbone and side chain polymers were used during the fractionization, using a Soxhlet apparatus under N2 for 24 hours. The soluble fractions were isolated by vacuum-removal of solvent. Usually, the total soluble fractions were less than 5 % of the product. The major insoluble fraction was PE graft copolymer, which was completely soluble in xylene or trichlorobenzene at elevated temperatures. 

Graft copolymer, polyclhylene-gra/f-poly(propylcnc oxide) (PE-g-PPG), has been synthesized by ring opening anionic polymerization of propylene oxide with a phosphazene catalyst and hydroxylated polyethylene (Mn = 12400, [OH] = 5 units/chain). Polymerization of propylene oxide was carried out in tetraline at 120 °C for 20 hours. The 13C NMR analysis of PE-g-PPG suggested that all the hydroxyl groups were consumed for propylene oxide polymerization (Fig. 6). 

Effect of Substrate. Again, polyethylene and ethylene-propylene copolymers are better substrates for block formation than polypropylene (Table XI). Polyethylene is better than polypropylene, and a polyethylene-polypropylene-polyethylene type of block polymer is better than polyethylene. This agrees with what has been found for AFR polymers containing methylvinylpyridine and acrylonitrile. It also supports our belief that AFR polymers are formed by the growing of a free radical polymer onto active ends of anionic polymer chains. If it were a random grafting reaction, it would be hard to explain why a propylene polymer with a more vulnerable tertiary hydrogen should give a lower... 

Kostov, G.K. and Turmanova, S.C. 1997. Radiation-initiated graft copolymerization of 4-vinylpyridine onto polyethylene and polytetrafluoroethylene films and anion-exchange membranes therefrom. J Appl Polym Sci. 64 1469-1475. 

Another example of ionic graft copolymerization is a reaction carried out on pendant olefinic groups using Ziegler-Natta catalysts in a coordinated anionic-type polymerization. The procedure consists of two steps. In the first, diethylaluminum hydride is added across the double bonds. In the second the product is treated with a transition metal halide. This yields an active catalyst for polymerizations of a-olefms. By this method polyethylene and polypropylene can be grafted to butadiene styrene copolymers. Propylene monomer polymerization results in formations of isotactic polymeric branches ... 

Some efforts have also been directed towards the preparation of anion exchange membranes from polymer films (approach b ). Generally, these polymers, e.g., polymer films of hydrocarbon polyethylene and polypropylene or fluorocarbon origin (ETFE, PVDF), are insoluble in solvents. The method most commonly used consists in grafting vinyl monomers, such as styrene, onto polymer films followed by subsequent chemical modifications, such as chloromethylation-amination instead of sulfona-tion [6-8]. 

Separation and Concentration of Anionic Organic Electrolytes by Electrotransport through Polyethylene Films Grafted with Cationic Polymers... 

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