Copolymers heterocyclic

Block, Gr ft, ndSta.r Copolymers. A host of copolymers of these types have been prepared. They iaclude block copolymers from S-caprolactam and PTMEG as well as block copolymers from PTHF and other cationicaHy polymerizable heterocycles, including... 

There is also a large number of synthetic heterocyclic compounds with other important practical applications, as dyestuffs, copolymers, solvents, photographic sensitizers and developers, as antioxidants and vulcanization accelerators in the rubber industry, and many are valuable intermediates in synthesis. 

Role of Microstructure and Architecture 5.2.3.1 Aromatic and Heterocyclic Block Copolymers... 

Figure 5.13 Heterocyclic aromatic block copolymers obtained by aromatic nucleophilic substitution.

Heterocyclic block copolymers, 282-284 Heterocyclic diamines, rigid, 281 Heterocyclic polymers, structure-property relationships in, 273-274 Heterocyclic ring formation, PQ and PPQ synthesis by, 309-310 Hexadecyltrimethylammonium bromide (HTMAB), 549-550 Hexamethylene diisocyanate (HDI), 199, 210. See also HDI trimer Hexamethylenediamine-adipic acid salt, 169, 170... 

Pyrrole derivatives substituted in positions 1-, 3-, or 4- have also been electrochemically polymerized (positions 2- and 5- must be free for polymerization). Besides homopolymers, copolymers can also be prepared in this way. Other nitrogen heterocycles that have been polymerized by anodic oxidation include carbazole, pyridazine, indole, and their various substitution derivatives. 

By contrast, much of the work performed using ruthenium-based catalysts has employed well-defined complexes. These have mostly been studied in the ATRP of MMA, and include complexes (158)-(165).400-405 Recent studies with (158) have shown the importance of amine additives which afford faster, more controlled polymerization.406 A fast polymerization has also been reported with a dimethylaminoindenyl analog of (161).407 The Grubbs-type metathesis initiator (165) polymerizes MMA without the need for an organic initiator, and may therefore be used to prepare block copolymers of MMA and 1,5-cyclooctadiene.405 Hydrogenation of this product yields PE-b-PMMA. N-heterocyclic carbene analogs of (164) have also been used to catalyze the free radical polymerization of both MMA and styrene.408... 

Cao and coworkers synthesized three series of copolymers 348 [426], 349 [427], 350 [428], and 351 [429], exploiting random copolymerization of fluorene fragments with dibromo-derivatives of Se,N and S,N heterocycles (Scheme 2.55). Fluorene-benzoselenadiazole... 

Modern life and civilization opened the way to other important practical applications of heterocycles, for example dyestuffs, copolymers, solvents, photographic sensitizers and developers, and in the rubber industry antioxidants and vulcanization accelerators. Some of the sturdiest polymers, such as Kevlar, have aromatic rings. Melamines (2,4,6-triamino-substituted s-triazines) are monomers with numerous applications as both homopolymers and copolymers. Scheme 9 shows a few examples of compounds with various applications in our daily life, having in common the same building block, the aromatic s-triazine. 

Copolymers bearing keto-fj-heterocyclic units COCH Het are good systems for the comparative study of the specific tautomeric equilibrium of the B units (42) on model compounds (CH ) CCOCH Het. and on well defined macromolecular chains ... 

Copolymers with pendant furan moieties have been used to synthesize new polymer structures by exploiting the reactivity of this heterocycle toward various dienophiles117, e.g. [60]fullerene112b. 

Brian Einsla was born in Wilkes-Barre, PA, in 1978. He earned his Bachelor of Science degree in 2000 in Chemistry at Virginia Polytechnic Institute and State University. He is currently a fourth-year Ph.D. candidate in the Macromolecular Science and Engineering program at VPI SU. His research interests have centered around sulfonated heterocyclic copolymers for fuel cell applications, including polyimides, polybenzoxazoles, and polybenzimidazoles. 

Recent work on the synthesis, structure and some properties of macromolecules bearing furan rings is discussed. Two basic sources of monomers are considered, viz. furfural for monomers apt to undergo chain polymerization and hydroxymethylfurfural for monomers suitable for step polymerization.Within the first context, free radical, catiomc and anionic systems are reviewed and the peculiarities arising from the presence of furan moieties in the monomer and/or the polymer examined in detail. As for the second context, the polymers considered are polyesters, polyethers, polyamides and polyurethanes. Finally, the chemical modification of aU these oligomers, polymers and copolymers is envisaged on the basis of the unique reactivity of the furan heterocycle. 

Interestingly, Hedrick and coworkers reported a metal-free approach for the synthesis of star-shaped copolymers. They synthesized star-shaped PCLs by the ROP of eCL initiated by polyols in the presence of unencumbered N-heterocyclic carbenes [87]. 

Arylene ether/imide copolymers were prepared by the reaction of various amounts 4,4 -carbonylbis[Ar-(4 -hydroxyphenyl)phthalimide] and 4,4 -biphenoi with a stoichiometric portion of 4,4 -dichlorodiphenyl sulfone in the presence of potassium carbonate in NMP/CHP [55]. To obtain high molecular weight polymer, the temperature of the reaction was kept below 155 °C for several hours before heating to >155°C in an attempt to avoid undesirable side reactions such as opening of the imide ring. The imide ring is not stable to conditions of normal aromatic nucleophilic polymerizations unless extreme care is exercised to remove water. Special conditions must be used to avoid hydrolysis of the imide as previously mentioned in the section on Other PAE Containing Heterocyclic Units and as practiced in the synthesis of Ultem mentioned in the Historical Perspective section. 

The five-membered cyclic amide pyrrolidone has achieved widespread attention in the area of heterocyclic polymers since the first preparation and polymerization reactions of l-vinylpyrrolidin-2-one (1) were reported in the early 1940s. Poly(vinylpyrrolidone) (2) and its copolymers are among the most thoroughly studied heterocyclic addition polymers (B-74MI11100). Monomer (1) is readily polymerized (B-77MI11100) both free radically and ionically (Scheme 1). The former method is by far the most important, and allows the preparation of a wide variety of copolymers. Interestingly, in the homopolymerization of vinylpyrrolidone (1), the molecular weight of the polymer obtained does not appear to be influenced by the initiator concentration or the reaction temperature. 

Simpler alkenylmorpholines, such as 4-vinylmorpholine (148), would seem to be interesting heterocyclic monomers. While monomer (148) is unstable, substituted enamines such as 1-morpholino-l-butene (149) have been incorporated into copolymers with acrylonitrile. Copolymers containing up to 30% of units derived from monomer (148), however, may be prepared according to Scheme 45 (70MI11102). 

Substituted pyrazolin-5-one heterocycles (187) have been coupled (Scheme 90) with a diazotized styrene-divinylbenzene copolymer (188) for purposes of forming a metal com-plexing resin (73MI11104). Resin (189) exhibited varying degrees of complexing ability with Cu +, Ni, Co, Mg2+ and Zn2+ ions. Selectivity was controlled primarily by the size of the R and R substituents. When R = Me and R = Pr1, for example, the resin exhibited a predominant selectivity for Cu2+ ion. 

The synthesis of poly(vinyl acetals) (252) represents another example of generating a heterocycle, in this case the 1,3-dioxane nucleus, by application of a polymer modification reaction. Generally, the polymer modified is poly(vinyl alcohol) (180) or one of its copolymers. The 1,3-dioxane ring is generated (Scheme 122) by an acid-catalyzed acetalization reaction with an aldehyde, although ketones have also been reacted. A review (71MI11102) is available covering synthesis, properties and applications of the two most common and industrially important poly(vinyl acetals), poly(vinyl butyral) and poly(vinyl formal), as well as many other functional aldehydes that have been attached. 

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