Telechelic polyethers

In addition, telomers which exhibit carboxy end-groups have been esterified with telechelic polyether diols and a,co-difunctional PDMS have been mainly used as the central block, as in the three following examples [132-134] ... 

Rice, D. Ihlenfeld, J Contact lens containing a fluorinated telechelic polyether. US Patent 4,440,918, Apr 3, 1984. 

The oxidative polymerization of 2,6-dimethylphenol (invented by Hay et al. [91], see also Chap. 8) and the polymerization of potassium 4-bromo-2,6-dim-ethylphenoxide (see Formula 16.6) have both the character of CCPs. The former CCP needs oxygen as reaction partner and a Cu amine complex as catalyst. Heitz et al. [92] observed that contrary to a normal polycondensation high oligomers were formed at low conversions, and he formulated a speculative radical-cation mechanism. The CCP of 4-bromophenoxide salts needs Cu " or other oxidizing metal ions as reaction partners and also involves a radical-cation mechanism [93]. When 4-methyl- or 4-tert.butylphenol are added as initiators, linear chains having one OH end group are formed, whereas addition of tetramethyl bisphenol yields telechelic polyethers (see Formula 15.6). 

Telechelic polymers rank among the oldest designed precursors. The position of reactive groups at the ends of a sequence of repeating units makes it possible to incorporate various chemical structures into the network (polyether, polyester, polyamide, aliphatic, cycloaliphatic or aromatic hydrocarbon, etc.). The cross-linking density can be controlled by the length of precursor chain and functionality of the crosslinker, by molar ratio of functional groups, or by addition of a monofunctional component. Formation of elastically inactive loops is usually weak. Typical polyurethane systems composed of a macromolecular triol and a diisocyanate are statistically simple and when different theories listed above are... 

The telomerisation of tetrafluoroethylene was photochemically initiated in the presence of oxygen, leading to telechelic fluorinated polyethers 5 [65] ... 

Such compounds have been commercialised by the Montefluos-Ausimont Company, called FOMBLIN [66]. They are composed of two groups Fomblin Y, produced by a fluorination of 5, are non functional polyethers CF3(CF20)x (C2F40)yC2F5 whereas Fomblin Z are obtained by chemical change of 5 leading to the following telechelics ... 

The production of liquid short-chain difunctional polymers by anionic polymerization is of considerable technological interest and importance, and has attracted much attention in recent years, since it offers an analogous technology to that of the polyethers and polyesters used in urethane polymers. Such liquid telechelic polydienes could thus lead, by means of chain extension and crosslinking reactions, directly to castable polydiene networks [161,162]. 

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-... 

The synthesis of telechelics by ring opening has attracted great interest because of the commercial potential of the resulting compounds, such as polyether polyols. The end groups are introduced by initiation, end capping, or transfer reactions. 

The quadrupole hydrogen-bonded unit can be employed in the chain extension of telechelic ohgomers such as polysiloxanes, polyethers, polyesters, and polyacrbonates (Fohner et al., 2000). Thus the electrophilic isocyanate group (-NCO) of synthon (3 in Fig. 1.5) can be reacted with common nucleophilic end groups (-OH or -NH2) of telechelic ohgomers, resulting in supramolecular polymers by chain extension (Fig. 1.6). Thus the material properties of telechelic polymers have been shown to improve dramatically upon functionahzation with synthon, and materials have been obtained that combine many of the mechanical properties of conventional macromolecules... 

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... 

Dimerized fatty acids (DFA) can be used as an alternative to polyether segments in TPE. The polyester elastomers based on DFA were first prepared by Hoeschele [42]. The properties affecting the degradation stability were improved, but the properties at lower temperatures were unsatisfactory, because the higher glass transition temperature was influenced by the lengths of the amorphous segments. DFA can be coupled with diols and diamines to synthesize telechelic polyesters (Scheme 14) and polyamides, respectively. 

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