Telechelic polyethylene

Ethylene polymerized with diethyl peroxydicarbonate contains terminal ester groups (41). Using C-labeled cyclohexane peroxydicarbonate, the fate of the primary radicals during the polymerization of methyl methacrylate (MMA) and styrene has been studied (42). Although this reference includes no detailed analysis of the products, it indicates that ROOCO-terminated polystyrene telechelics may be obtained by this technique. A similar method has been used for the preparation of telechelic polybutadiene (43). The carbonate end groups are easily modified into terminal hydroxyl groups by hydrolysis. Hydrogenation of the carbonate functionahzed telechelic polybutadiene, followed by hydrolysis, srields hydroxy-terminated polyethylene telechelics. 

If mono-hydroxyl functionalized polyethylene glycol), HO-PEG, is added to Ca(NTMS2)2.THF2, then addition of LA affords the diblock PEG-b-PLA (Mn= 15,500, Mn calc = 15,500, Mw/Mn = 1.03).832 Using a similar strategy the reaction of CaFI2 with telechelic diol HO-(PEG)-OH, followed by polymerization of L-LA results in a triblock structure, PLA-b-PEG-b-PLA of narrow polydispersity (1.02-1.08).835 836 Triblock copolymers of morpholine-2,5-diones with PEO have also been prepared in this manner.837... 

Amphiphilic triblock copolymers were prepared from polyethylene glycol) (PEG) [35], Starting from PEG segments of different lengths (Mw = 200,400, MO, 1000 and 1500) and with different end-groups (e,g, hydroxy, acetoxy, benzoyl, oleoyl, phenylurethane), telechelic macroazoinitiators are first prepared. By polymerization of styrene, a wide range of original copolymers are produced ... 

Nonionic amphiphilic telechelic polymers consisting of polyethylene oxide with polyhedral oligosilsesquioxane, POSS, termini were prepared by Mather [3] and used as surfactants and thickening agents. The hydrophobicity of these amphiphilic telechelics, (III), was controlled by varying the molecular weight of the polyethylene oxide component. 

In the initiation reaction a carbonate group is fixed at the polyethylene chain-end, and in the termination reaction a saturated end-group is formed. Although these experiments failed to give telechelics they showed that primary radicals from percarbonates will give carbonate end-groups, and telechelics should be obtainable if this side reaction can somehow be avoided. 

Again the efficiency is >0.9 and the ester functionality is exactly 2. The ester groups can be converted to carboxylic acids. The whole chain can be hydrogenated to obtain telechelic polyethylene with ester or hydroxyl end-groups. These telechelics can replace poly(tetrahydrofuran) in the modification of polyesters. The ester end-groups can be used directly in a transesterification process. 

Microwave irradiation Grafting onto method Various catalysts are used [4,4 -Azobis (4-cyanovaleric acid)] Telechelic polymers, polyethylene glycol, poly-dimethyl siloxane... 

Cocondensation of macromers containing trialkoxysilyl groups with modified polystyrene (PS), polyoxazoline, polyimide, polyethylene glycol (PEG), polyether-ketones, polymethyl methacrylate, and derivatives of polytetramethylene oxide was established as convenient procedure for the preparation of telechelic polymer net-... 

Telechelic polystyrene and polyethylene containing a hydroxyl and a carboxylic end group are obtained by copolymerizing a small quantity of 2-methylene-1,3-dioxepane with a large quantity of st5Tene or ethylene, and then hydrolyzing the resulting polymers (reactions 10 and 11). 

Many other oxidizing agents can he used to cleave polymer chains. For example, fuming nitric acid cleaves polyethylene to yield carboxyl telechelic polyethylene (455-459). However, nitration of the polymer chain is a side reaction. The nitro groups can be converted to ketones without further reduction of molecular weight (460). 

Because of its relative ease of synthesis from inexpensive starting materials, the ureido pyrimidinone (UPy) supramolecular motif has been widely exploited in recent years (Figure la). Appending UPy residues at the terminal positions of telechelic polymers such as end-functional polysiloxanes and polyethylene-co-butylene (pE-co-B), transforms previously free flowing, liquid starting materials into tough, elastomeric solids (Scheme 1). 

Watson and Wagener [95] reported a tandem ADMET polymerization/ hydrogenation approach to acetoxy-end-functionalized telechelic polyethylene. DCD was polymerized in the presence of 9-decenyl acetate to form the corresponding di-ester-functionalized homo-telechelic polymer. The crude unsaturated polymer was intimately mixed with silica gel and exposed to 120 psi of H2 at 90 °C. The silica gel was added to suppress catalyst homo-dimerization, and the hydrogenated polymer was recovered as the di-ester-functionalized telechelic polyethylene with a molecular weight of 1.5 X 10 g moD fDP = 48) and a PDI of 1.9. 

The chemical modification of homopolymers such as polyvinylchloride, polyethylene, poly(chloroalkylene sulfides), polysulfones,poly-chloromethylstyrene, polyisobutylene, polysodium acrylate, polyvinyl alcohol, polyvinyl chloroformate, sulfonated polystyrene block and graft copolymers such as poly(styrene-block-ethylene-co-butylene-block-styrene), poly(1,4-polybutadiene-block ethylene oxide), star chlorine-telechelic polyisobutylene, poly(lsobutylene-co-2,3-dimethy1-1,3-butadiene), poly(styrene-co-N-butylmethacrylate) cellulose, dex-tran and inulin, is described. 

Telechelic macromers have often been used for making block copolymers. Thus the elastomic fibre, spandex (e.g. Lycra), is made from poly-THF, H(0(CH2)4) 0H, with a diisocyanate (to form a urethane), and the thermoplastic elastomer, Hytrel, is composed of blocks of poly-THF and terephthalic esters. Non-ionic surfactants are often block copolymers of polyethylene oxide/polypropylene oxide (prepared by anionic polymerization). 

Tg measurements have been performed on many other polymers and copolymers including phenol bark resins [71], PS [72-74], p-nitrobenzene substituted polymethacrylates [75], PC [76], polyimines [77], polyurethanes (PU) [78], Novolac resins [71], polyisoprene, polybutadiene, polychloroprene, nitrile rubber, ethylene-propylene-diene terpolymer and butyl rubber [79], bisphenol-A epoxy diacrylate-trimethylolpropane triacrylate [80], mono and dipolyphosphazenes [81], polyethylene glycol-polylactic acid entrapment polymers [82], polyether nitrile copolymers [83], polyacrylate-polyoxyethylene grafts [84], Novolak type thermosets [71], polyester carbonates [85], polyethylene naphthalene, 2,6, dicarboxylate [86], PET-polyethylene 2,6-naphthalone carboxylate blends [87], a-phenyl substituted aromatic-aliphatic polyamides [88], sodium acrylate-methyl methacrylate multiblock copolymers [89], telechelic sulfonate polyester ionomers [90], aromatic polyamides [91], polyimides [91], 4,4"-bis(4-oxyphenoxy)benzophenone diglycidyl ether - 3,4 epoxycyclohexyl methyl 3,4 epoxy cyclohexane carboxylate blends [92], PET [93], polyhydroxybutyrate [94], polyetherimides [95], macrocyclic aromatic disulfide oligomers [96], acrylics [97], PU urea elastomers [97], glass reinforced epoxy resin composites [98], PVOH [99], polymethyl methacrylate-N-phenyl maleimide, styrene copolymers [100], chiral... 

Benzothiozolon-3-yl Acetic Acid-telechelic Polyethylene Oxides (PEG Esters)... 

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