Photoinitiated polymerization of methyl methacrylate with benzoin methyl ether. III. Independent photogeneration of the ether radical

Evidence is presented for initiation of MMA polymerization by the α-methoxybenzyl (ether) radical, photogenerated by H abstraction from benzyl methyl ether, utilizing benzophenone as the H-ab-stracting agent. The results support previous reports on the initiating ability of ether radical, photogenerated from ¹⁴C-labeled benzoin methyl ethers. Independent generation of one or both of the radicals derived from unsymmetrical initiators is more broadly applicable. The potential utility of this technique for providing insights into the photoefficiencies of commercially important photoinitiators, which produce initiator radicals by intramolecular bond cleavage, is discussed.     

Recent advances in micellar electrokinetic chromatography

This review contains nearly 200 reference citations, and covers advances in electrokinetic capillary chromatography based on micelles, including stabilized micelle complexes, polymeric and mixed micelles from 2003-2004. Detection strategies, analyte determinations, and applications in micellar electrokinetic capillary chromatography (MEKC) are discussed. Information regarding methods of analyte concentration, analyte specific analyses, and nonstandard micelles has been summarized in tabular form to provide a means of rapid access to information pertinent to the reader.     

Post-polymerization modification of aromatic polyimides via Diels-Alder cycloaddition

We report a facile post-polymerization modification route to functionalized aromatic polyimides via Diels-Alder cycloaddition. Aromatic polyimides are important, versatile high-performance polymers; however, their structural diversity is restricted by the requirements of the step-growth polymerization. We prepared polyimides with alkynes in their main-chain as macromolecular dienophiles and quantitatively grafted tetraphenylcyclopentadienone based dienes. The resulting solution-processable, wholly aromatic polyimides show a considerable increase in surface area due to the induced conformational changes and bulky, rigid, and contorted molecular structures. The orthogonality of the reaction is exploited to insert functional groups, namely bromine and sulfonates, along the polymer backbone. In a further extension, the phenylene segments undergo cyclodehydrogenation to form nanographene segments within the polymer chains. The Diels-Alder cycloaddition onto polyimides is therefore demonstrated to be an effective, widely applicable route to tunable high-performance polymers with value-added functionality and thus considerable potential in a wide range of advanced materials.