Polymers telechelic

Homo-telechelic polymers with two or sometimes more identical end groups are of great industrial importance, particularly for polyurethane synthesis [1-4]. 

While end-functional polymers are clearly important industrial products for materials synthesis, they are also interesting from an academic point of view. Many complex macromolecular architectures can be realized from end-functional polymeric starting materials. Two mono-telechelic polymers can, for example, be joined to form a diblock copolymer, or several such polymers can be joined to form star-like polymers. Mono-telechelic polymers can also be attached to a linear, multifunctional polymer to yield graft copolymers. Depending on the functional end group, such polymers can attach to macroscopic or nanoparticle surfaces or form conjugates with bio-oligomers [5] or biomacromolecules [6]. 

Handbook of Metathesis VoL 3 Polyma- Synthes, Second Edition. 

Aagg = 367rv la . For an alkane hydrophobe, v Uric A, where ric is the number of carbon atoms in the alkane chain [see Eq. (12-1)]. Thus, for = 16, we find the relationship Aagg 20/a, where a is in nm. Because the head groups of the telechelic 

Because the telechelic polymer has two tails or stickers, separated by a long hydrophilic chain, the micelles formed by telechelics are expected to contain loops and bridges, as depicted in Fig. 5-16. Loops are expected to predominate at concentrations 

When A/x/kfiT 1, there will be few free stickers. According to the classical theory for gels, the modulus of a telechelic gel should be simply given by Eq. (5-2), Go = vksT, 

A plot of viscosity versus shear rate for a model HUER polymer is shown in Fig. 5-20, and compared to the dynamic viscosity versus frequency. Note that the Cox-Merz rule (see Section 1.3.1.5) fails in that at the frequency (o 1 sec ) where the dynamic viscosity- 

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E. J. Goethals, ed., Telechelic Polymers Sjsthesis and Applications, CRC Press, Boca Raton, Fla., 1989. 

Unfortunately, because self-condensation of silanols on the same silicone can occur almost spontaneously, the reaction of disdanol or trisilanol compounds with telechelic sdanol polymers to form a three-dimensional network is not feasible. Instead, the telechelic polymers react with cross-linkers containing reactive groups such as alkoxysdanes, acyloxysdanes, silicon hydrides, or methylethyloximesilanes, as in the reactions in equations 18—21 (155). 

The quantum yield of polymerization is 6.72 and for photoinitiation < / = 2.85 x 10 . The polystyrene produced with this initiator shows photosensitivity when irradiated with UV light (A = 280 nm). This polymer, which carries two photosensitive end groups of - SC(S) N(CH3)2, behaves as a telechelic polymer and it is useful for production of ABA block copolymer. 

Transfer constants of the methacrylate macromonomers in MMA polymerization do not depend on the ester group but are slightly higher for MAA trimer. Compounds 72 and 73 are derived from the MMA trimer (67) by selective hydrolysis or hydrolysis and reesterification respectively. They offer a route to telechelic polymers. 

Heitz, W. in Telechelic Polymers Synthesis and Applications, Goethais, E.J., Ed. CRC Press Boca Raton, Florida, 1989 p 61. 

A telechelic polymer is a di-end-functional polymer where both ends possess the same functionality. 

When a polymer is prepared by radical polymerization, the initiator derived chain-end functionality will depend on the relative significance and specificity of the various chain end forming reactions. Tlius, for the formation of telechelic polymers ... 

Diol-functionalized telechelic polymers have been desired for the synthesis of polyurethanes however, utilizing alcohol-functionalized a-olefins degrades both 14 and 23. Consequently, in order for alcohols to be useful in metathesis depolymerization, the functionality must be protected and the oxygen atom must not be /3 to the olefin or only cyclic species will be formed. Protection is accomplished using a/-butyldimcthylsiloxy group, and once protected, successful depolymerization to telechelics occurs readily. 

Dimethylphenol, synthesis of, 383 /V,/V-Dimorpholinodicthyl ether (DMDEE), 225, 230 Dinitrile-diamine polyamides, 158 Dioctyltin dilaurate, 232 Diol-functionahzed telechelic polymers, 457... 

Kennedy and co-workers 2 117) used the changing effect of the initiation ability of the Lewis acids according to Eq. (17) and the termination tendency of the anion formed according to Eq. (18) in order to obtain telechelic polymers , block copolymers and graft copolymers in a controlled manner. Quantum chemical calculations provide the possibility to discuss structural influences which work on the equilibrium Eq. (19) and therefore on the stability of the two adjacent ions. 

Synthesis of PIB prepolymers. fm-Chlorine-telechelic PIB (Mn=4,000 MVf/Mn 1.09) (7), and an allyl-telechelic PIB (Mn=9,500 Mw/Mn 1.14) (7,8) were prepared by living carbocationic polymerizations. The tert-chlorine ended PIB was quantitatively dehydrochlorinated (9) to -C(CH3)=CH2 terminated polymer. Both olefin-telechelic PIBs were then hydroborated and oxidized (10) to prepare the primary hydroxyl termini. The hydroxyl-telechelic polymers were esterified with methacryloyl chloride to methacrylate-telechelic PIBs, MA-PIB-MA (11). 

Finally, some polymerisations can be directed such that the final oligomer or polymer contains two or more reactive end groups capable of extended polymerisation with different monomers. These materials are named telechelic macromers or telechelic polymers. 

Boraindane 178 <1996CHEC-II(8)889> was applied to the preparation of new telechelic polymers, including poly(methylmethacrylate) and poly(trifluoroethyl acrylate) containing two reactive OH groups at the polymer chain <2004MM6260>. 

Difunctional Iniferter X-X > X-QA X Telechelic polymer, AB- or ABA-type block copolymer... 

The resulting polymers always have the same functional group X at both chain ends. Therefore, telechelic polymers can be readily synthesized by the two-component iniferter system. An example is the polymerization of several monomers with 4,4J-azobiscyanovaleric acid (16) and dithiodiglycolic acid (17) as the initiator and the chain transfer agent, respectively, to synthesize the polymers having carboxyl groups at both chain ends [69]. 

Nair et al. studied the kinetics of the polymerization of MMA at 60-95 °C using N,1SP-diethyl-NjW-di(hydroxyethyl)thiuram disulfide (30a) as the thermal in-iferter [142]. The dependence of the iniferter concentration on the polymerization rate was examined. The chain transfer constant of the propagating radical of MMA to 30a was determined to be 0.23-0.46 at 60-95 °C, resulting in the activation energy of 37.6 kj/mol for the chain transfer. Other derivatives 30b-30d were also prepared and used to derive telechelic polymers with the terminal phosphorus, amino, and other functional aromatic groups [143-145]. Thermal polymerization was also investigated with the end-functional poly(St) and poly(MMA) which were prepared using the iniferter 13 [146]. 

Telechelic polymers usually bear monofunctional groups at each of their extremities. However, sometimes each end-group is bifunctional, such as in a, co-bis-unsaturated telechelics, or trifunctional as in a, co-bis(trialkoxysilyl) telechelics wherein they participate in crosslinking by the sol-gel reactions (hydrolysis and condensation of alkoxysilane groups). 

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... 

Dusek, K., Networks from telechelic polymers theory and application to polyurethanes, in Goethals, E. J. (ed.), Telechelic Polymers Synthesis and Applications, CRC Press, Boca Raton, FL, (1989), pp. 289-360. 

New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers) End Reactive Polyisobutylenes by Semicontinuous Polymerization... 

We have previously reported the results of careful investigations of the solution carbonation (8) and oxidation (9) of polymeric organolithium compounds. These studies have been extended to the investigation of solid-state carbonation reactions and these results are reported herein. In addition, a new method has been developed for the synthesis of telechelic polymers with primary amine end-group... 

There are 22 chapters in the book and they cover the most important aspects of polymers as drugs, prodrugs, dmg delivery systems, and in situ prostheses. The major features promulgated are synthesis, derivatization, degradation, characterization, application, and evaluation techniques as well as new biodegradable materials, assemblies, hydrogels, telechelic polymers, derivatized polysaccharides, micro- and nanoparticles, mimetic... 

Figure 6. Expected change in the equilibrium modulus, Gg, with respect to its ideal value for a perfect network, Gg produced by a 3% change in conversion, AC, functionality, Af the molar ratio [OH]/[NCO], Ar, and cyclization, AC in dependence on conversion. The data refer to a system composed of. trifunctional telechelic polymer and difunctional coupling agent. (Reproduced with permission from Ref. 42. Copyright 1987 CRC Press.)...

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