Diels-Alder polymers

A cation radical chain cycloaddition-polymerization catalysed by tris(4-bromophenyl)aminium hexachloroantimonate has been reported to afford polymers with an average molecular weight up to 150000. Both cyclobutanation and Diels-Alder polymers were obtained. " The reactivity of the phospine radical cation towards nucleophiles was studied. Tributylphosphine reacted with l,l-dimethyl-4,4-bipyridinium (methyl viologen, MV) in the presence of an alcohol or thiol (RXH X = O, S), which resulted in the gradual formation of the one-electron reduced form... 

Diels-Alder mechanism. It was found that those polymers which had the least weight loss in the isothermal aging study were derived from those monomers which by DSC polymerized to the greatest extent by a Diels-Alder mechanism. It was inferred therefore that if similar considerations apply to the copolymers of bismaleimides and bisbenzocyclobutenes then these materials too might be the result of predominantly Diels-Alder type polymerizations. To the extent to which these conclusions are correct, the enhanced thermal stability of the bisbenzocyclobutene/bismaleimide copolymers is likely to be due to their being Diels-Alder polymers of some sort. 

Fig. 38. Proposed structure of the Diels-Alder polymer derived from l-(4-benzocyclobutenyl)-2-phenylethylene 78a...

Several di-dienes have been successfully utilized in copolymerization reactions with di-dienophiles. The diene 2-hydroxymethylbutadiene offers a functional handle by which two butadiene portions may be linked to form a di-diene (5). Copolymerization reactions of these di-dienes with a series of fcis-maleimides and quinone in refluxing dime-thylformamide afford Diels-Alder polymers with a range of physical properties. 

Kuramoto N, Hayashi K, Nagai K (1994) Thermoreversible reaction of Diels-Alder polymer composed of difurufuryladipate with bismaleimidodiphenylmethane. J Polym Sci A Polym Chem 32 2501-2504... 

Diels Alder polymers can be obtained via the cyclo-pentadienone route [3,17]. New CPDs were synthesized according to the following reaction scheme [18] ... 

Figure 12. Synthesis of Diels Alder polymers via the AB route...

Discuss Diels-Alder polymers giving at least four examples and showing all the structures of the starting materials and the products. 

Diels-Alder polymers n. Polymers created as a result of a Diels-Alder reaction, by which a 1,3-diene reacts via addition to another unsaturated molecule (the dienophile) to form a cyclic adduct. Morrison RT, Boyd RN (1992) Organic chemistry, 6th edn. Prentice-Hall, Englewood Cliffs, NJ. Smith MB, March J (2001) Advanced organic chemistry, 5th edn. John Wiley and Sons, New York. 

Anionic and Cationic Polymerizations o Radical Polymerization Advances o Coordination Polymerizations 0 Step-Growth Polymerization Advances 0 Synthesis of Tactic Polymers o Stereoblock Copolymers o Dispersion Polymerizations o Cellulosic Graft Copolymers o Diels-Alder Polymer Forming Reactions o A New Path To Phenolic Resins o Nitrogen Heterocycle Polymerizations o Optically Active Polymers o Poly (Phenylene Sulfide) o Poly (Aryl Ethers) o (Poly (Aryl Ether Sulfones) o Epoxy and Isocyanate Resin Replacement o Azlactone Functionalized Oligomers o Epoxy Resin-Isocyanate Reactions o Chelating Polymers o Oxazoline Functionalized Polymers o Poly (Alkyl Methacrylates) o Macromers... 

The hydrocarbon resins can be produced by a simple thermal polymerization process (48-50) or by Lewis acid catalyzed reaction (51). The thermal process is carried out at a high temperature in the range of 200-280°C and a reactor pressure above 300 psig. At temperatures below 200°C, the Diels-Alder polymers are formed. They are not desirable in most resins because they are insoluble in aromatic solvents. If reaction temperature exceeds 280°C, decomposition of the resins would occur. 

Various polymerization route with unique starting monomer [64] have been developed, e.g., topochemical poly(diacetylene) synthesis with pyrrole-, thiophene-, -Si-groups dienophilic addition of maleic imides, Diels-Alder polymers via cyclopentadienone derivatives. 

Chou Chou L, and Liu Ying-Ling. High performanee thermosets from a curable Diels-Alder polymer possessing benzoxazine groups in the main chain. J. Polym. Sci. Part A. 46 no. 19 (2008) 6509-6517. 

Mukamal, F. W. Harris, and J. K. Stille, Diels-Alder Polymers III. Polymers Containing Phenylated Phenylene Units," J. Polym. Sci., 5 2721 (1967). 

Diels-Alder polymers. This type of polymerization differs from Method 1 in that a bis(diene) is not employed. Rather, a dienophile reacts with a diene to yield an intermediate that can be converted to another diene by heating. These intermediates ([32] and [33]) are not isolated, but are formed and react in situ. Equation (III-12) depicts the course of the reaction of fV,iV -hexa-methylenebis(maleimide) with 2,5-dimethyl-3,4-diphenylcyclopentadienone (13). Peroxide-catalyzed cross-linking of these substituted cyclopentadienone derived polymers has been patented (5). Polymers treated in this way exhibited improved toughness, better stress cracking, and chemical resistance. 

Adzima J., Aguiue H., Kloxin C. J., Scott T. F. and Bowman C. N. (2008), Rheological and Chemical Analysis of Reverse Gelation in a Covalently Cross-Linked Diels-Alder Polymer Network , Atacra jo/ec fe5, 41, 9112-17. 

Mukamal H, Harris PW, Stille JK (1967) Diels-Alder polymers. III. Polymers containing phenylated phenylene units. J Polym Sci A Polym Chem 5 2721-2729... 

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