Telechelic polymers preparation

In the area of novel materials CMU protected (co)polymers prepared by ATRP except with CCI4 initiator and telechelic polymers prepared by CRP with MW > 20,000 (49) copolymers with a tme gradient segment (30) polar ABA block copolymers, (30) and well defined graft copolymers and segmented copolymers with one or more CRP blocks where the macroinitiator had been prepared by another polymerization process. (36) In addition, the use of tethered initiators allowed synthesis of hybrid core/shell copolymers. Pending applications disclose other novel polymeric materials. 

Tsarevsky, N.V. Sumerlin, B.S. Matyjaszewski, K. Step-growth click coupling of telechelic polymers prepared by atom transfer radical polymerization. Macromolecules 2005, 38 (9), 3558-3561. 

Table 4. Monofunctional Telechelic Polymers Prepared by Using Functional Initiators in ATRP...

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 ... 

Ebdon and coworkers22 "232 have reported telechelic synthesis by a process that involves copolymerizing butadiene or acetylene derivatives to form polymers with internal unsaturation. Ozonolysis of these polymers yields di-end functional polymers. The a,o>dicarboxy1ic acid telechelic was prepared from poly(S-s tot-B) (Scheme 7.19). Precautions were necessary to stop degradation of the PS chains during ozonolysis. 28 The presence of pendant carboxylic acid groups, formed by ozonolysis of 1,2-diene units, was not reported. 

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). 

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>. 

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]. 

Functionally terminal polymers are valuable material intermediates. The di- and polyfunctional varieties (telechelic polymers) have found theoretical (e.g., model network) and commercial (e.g., liquid rubber) applications (1, ). On the other hand, macromolecules with a functional group at one chain end (semitelechelic polymers) have been used to prepare novel macromolecular monomers (Macromers ), as well as block and graft copolymers ( -8). 

Results and. Discussion. There are basically two approaches to the preparation of telechelic and semi-telechelic polymers by anionic procedures. One method involves terminating living anionic polymers with suitable electrophiles another technique utilizes functionally substituted anionic initiators. 

The technique of the sulfur coupling reaction can be used also to prepare multiblock polymers. The technique of deactivation of carbanionic polymer with oxygen or sulfur is able to yield numerous interesting organic compounds such as novel macromolecular initiators, new macromolecular additives, and telechelic polymers. Finally, the coupling reactions can be used to build block polymers. 

C.D. Stokes, R.F. Storey, and J.J. Harrison, Process for preparing terminally functionalized living and quasiliving cationic telechelic polymers, US Patent 7 576161, assigned to Chevron Oronite Company LLC (San Ramon, CA) and The University of Southern Mississippi (Hattiesburg, MS), August 18,2009. 

The preparation of prepolymers [111] or macromers with functional end groups, so called telechelic polymers, is another approach to structurally unconventional architecture. The functional end groups are introduced either by functional initiation or end-capping of living polymers, or by a combination of the two. In this way, monomers that are not able to copolymerize can be incorporated in a copolymer. Telechelic prepolymers can be linked together using chain extenders such as diisocyanates [112]. In this process, it is essential that the structure and end groups of the prepolymers can be quantitatively and qualitatively controlled [113]. 

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 a subsequent investigation, the author, (3), prepared the nitroxide-mediated polymerization agent, 4,4-dimethyl-2- [ 1 -(2,2,6,6-tetramethylpiperidin-1 -yloxy)-ethyl] -4H-oxazol-5-one, (I), as a method of preparing telechelic polymers. 

For a synthetic polymer chemist the important question is whether the cyclization processes in cationic ring-opening polymerization can be controlled. If the preparation of linear polymer is attempted, then cyclic oligomers are undesirable side products. This is especially important in synthesis of telechelic polymers containing reactive end groups, because macrocycles would be unreactive admixtures. On the other hand, cyclic polymers, if prepared selectively, could be a valuable materials. 

Although several telechelic polymers of 1,3-dioxolane have been prepared by cationic polymerization, their application is limited due to their susceptibility to acid-catalyzed hydrolysis and/or depolymerization. By termination of living mono- and difunctional poly(l,3-dioxolane) with amines or phosphines, polymers containing one or two stable ionic (ammonium, phosphonium) end groups has been prepared [129,274],... 

The cyclization of 2-hydroxyethylamides is used commercially [278]. Various telechelic polymers were prepared using difunctional initiator,... 

Living polymerization processes pave the way to the macromolecular engineering, because the reactivity that persists at the chain ends allows (i) a variety of reactive groups to be attached at that position, thus (semi-)telechelic polymers to be synthesized, (ii) the polymerization of a second type of monomer to be resumed with formation of block copolymers, (iii) star-shaped (co)polymers to be prepared by addition of the living chains onto a multifunctional compound. A combination of these strategies with the use of multifunctional initiators andtor macromonomers can increase further the range of polymer architectures and properties. 

The versatility associated with nitroxide-mediated polymerizations, in terms of both monomer choice and initiator structure, also permits a wide variety of other complex macromolecular structures to be prepared. Sherrington201 and Fukuda202 have examined the preparation of branched and cross-linked structures by nitroxide-mediated processes, significantly the living nature of the polymerization permits subtlety different structures to be obtained when compared to traditional free radical processes. In addition, a versatile approach to cyclic polymers has been developed by Hemery203 that relies on the synthesis of nonsymmetrical telechelic macromolecules followed by cyclization of the mutually reactive chain ends. In a similar approach, Chaumont has prepared well-defined polymer networks by the cross-linking of telechelic macromolecules prepared by nitroxide-mediated processes with bifunctional small molecules.204... 

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