New Cation Radical Diels-Alder and Cyclobutanation Chemistry. Using the new 2-phase solvent system, the scope of cation radical Diels-Alder and cyclobutane cycloadditions has been greatly extended, so that even vinyl anisole and N-propenylcarbazole are effective dienophiles. The stereochemistry of numerous cyclobutanation and Diels-Alder reactions has been studied and distonic cation radical intermediates have been implicated in many of these cases.
Cation Radical Chain Cycloaddition Polymerization.We have found that cycloaddition polymerization can be effected by means of a cation radical chain mechanism. Triarylaminium salts are effective catalysts for both cyclobutanation and Diels-Alder polymerization. This represents a fundamentally new mechanism for polymerization. A completely different monomer set is appropriate for cation radical polymerization than for radical, cationic, or anionic polymerization.
Carbazole-containing polymers are of especial interest for electronic and electrooptic devices, and it has proved possible to synthesize novel types of carbazole polymers via cation radical cycloaddition polymerization. Some of these transparent, soluble polymers contain the carbazole unit as part of the main chain, and have molecular weights up to 200 K, are stable at or above 460 degrees. Still other types of carbazole polymers can be obtained by the ROMP polymerization of 5-carbazolylnorbornene monomers obtained via cation radical Diels-Alder cycloadditions.
New Photorefractive and Photoconductive Polymers. New classes of photorefractive and photoconductive copolymers are being synthesized for optoelectronic devices. Diblock polymers containing a block of a hole transport polymer and a block of a non-linear optic (NLO) polymer have been synthesized and are being evaluated as photorefractive materials.Corresponding random copolymers have also been prepared.
Anion Radical Chain Cycloaddition Polymerization. A new polymerization mechanism involving anion radical cycloaddition propagation steps is being developed.
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4 April 2000
Department of Department of Chemistry and Biochemistry, College of Natural Sciences, UT Austin
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